diff --git a/ChangeLog.d/check-return.txt b/ChangeLog.d/check-return.txt
new file mode 100644
index 0000000000..062b8a1729
--- /dev/null
+++ b/ChangeLog.d/check-return.txt
@@ -0,0 +1,12 @@
+Bugfix
+   * Failures of alternative implementations of AES or DES single-block
+     functions enabled with MBEDTLS_AES_ENCRYPT_ALT, MBEDTLS_AES_DECRYPT_ALT,
+     MBEDTLS_DES_CRYPT_ECB_ALT or MBEDTLS_DES3_CRYPT_ECB_ALT were ignored.
+     This does not concern the implementation provided with Mbed TLS,
+     where this function cannot fail, or full-module replacements with
+     MBEDTLS_AES_ALT or MBEDTLS_DES_ALT. Reported by Armelle Duboc in #1092.
+
+Changes
+   * Warn if errors from AES or DES functions are ignored. This is currently
+     supported on GCC-like compilers and on MSVC and can be configured by
+     setting MBEDTLS_CHECK_RETURN in config.h.
diff --git a/include/mbedtls/aes.h b/include/mbedtls/aes.h
index a74e413438..4662260cbe 100644
--- a/include/mbedtls/aes.h
+++ b/include/mbedtls/aes.h
@@ -175,6 +175,7 @@ void mbedtls_aes_xts_free( mbedtls_aes_xts_context *ctx );
  * \return         \c 0 on success.
  * \return         #MBEDTLS_ERR_AES_INVALID_KEY_LENGTH on failure.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_aes_setkey_enc( mbedtls_aes_context *ctx, const unsigned char *key,
                     unsigned int keybits );
 
@@ -193,6 +194,7 @@ int mbedtls_aes_setkey_enc( mbedtls_aes_context *ctx, const unsigned char *key,
  * \return         \c 0 on success.
  * \return         #MBEDTLS_ERR_AES_INVALID_KEY_LENGTH on failure.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_aes_setkey_dec( mbedtls_aes_context *ctx, const unsigned char *key,
                     unsigned int keybits );
 
@@ -213,6 +215,7 @@ int mbedtls_aes_setkey_dec( mbedtls_aes_context *ctx, const unsigned char *key,
  * \return         \c 0 on success.
  * \return         #MBEDTLS_ERR_AES_INVALID_KEY_LENGTH on failure.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_aes_xts_setkey_enc( mbedtls_aes_xts_context *ctx,
                                 const unsigned char *key,
                                 unsigned int keybits );
@@ -233,6 +236,7 @@ int mbedtls_aes_xts_setkey_enc( mbedtls_aes_xts_context *ctx,
  * \return         \c 0 on success.
  * \return         #MBEDTLS_ERR_AES_INVALID_KEY_LENGTH on failure.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_aes_xts_setkey_dec( mbedtls_aes_xts_context *ctx,
                                 const unsigned char *key,
                                 unsigned int keybits );
@@ -261,6 +265,7 @@ int mbedtls_aes_xts_setkey_dec( mbedtls_aes_xts_context *ctx,
 
  * \return         \c 0 on success.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_aes_crypt_ecb( mbedtls_aes_context *ctx,
                     int mode,
                     const unsigned char input[16],
@@ -308,6 +313,7 @@ int mbedtls_aes_crypt_ecb( mbedtls_aes_context *ctx,
  * \return         #MBEDTLS_ERR_AES_INVALID_INPUT_LENGTH
  *                 on failure.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_aes_crypt_cbc( mbedtls_aes_context *ctx,
                     int mode,
                     size_t length,
@@ -352,6 +358,7 @@ int mbedtls_aes_crypt_cbc( mbedtls_aes_context *ctx,
  *                     smaller than an AES block in size (16 Bytes) or if \p
  *                     length is larger than 2^20 blocks (16 MiB).
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_aes_crypt_xts( mbedtls_aes_xts_context *ctx,
                            int mode,
                            size_t length,
@@ -400,6 +407,7 @@ int mbedtls_aes_crypt_xts( mbedtls_aes_xts_context *ctx,
  *
  * \return         \c 0 on success.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_aes_crypt_cfb128( mbedtls_aes_context *ctx,
                        int mode,
                        size_t length,
@@ -444,6 +452,7 @@ int mbedtls_aes_crypt_cfb128( mbedtls_aes_context *ctx,
  *
  * \return         \c 0 on success.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_aes_crypt_cfb8( mbedtls_aes_context *ctx,
                     int mode,
                     size_t length,
@@ -498,6 +507,7 @@ int mbedtls_aes_crypt_cfb8( mbedtls_aes_context *ctx,
  *
  * \return         \c 0 on success.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_aes_crypt_ofb( mbedtls_aes_context *ctx,
                        size_t length,
                        size_t *iv_off,
@@ -584,6 +594,7 @@ int mbedtls_aes_crypt_ofb( mbedtls_aes_context *ctx,
  *
  * \return                 \c 0 on success.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_aes_crypt_ctr( mbedtls_aes_context *ctx,
                        size_t length,
                        size_t *nc_off,
@@ -604,6 +615,7 @@ int mbedtls_aes_crypt_ctr( mbedtls_aes_context *ctx,
  *
  * \return          \c 0 on success.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_internal_aes_encrypt( mbedtls_aes_context *ctx,
                                   const unsigned char input[16],
                                   unsigned char output[16] );
@@ -619,6 +631,7 @@ int mbedtls_internal_aes_encrypt( mbedtls_aes_context *ctx,
  *
  * \return          \c 0 on success.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_internal_aes_decrypt( mbedtls_aes_context *ctx,
                                   const unsigned char input[16],
                                   unsigned char output[16] );
@@ -668,6 +681,7 @@ MBEDTLS_DEPRECATED void mbedtls_aes_decrypt( mbedtls_aes_context *ctx,
  * \return         \c 0 on success.
  * \return         \c 1 on failure.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_aes_self_test( int verbose );
 
 #endif /* MBEDTLS_SELF_TEST */
diff --git a/include/mbedtls/des.h b/include/mbedtls/des.h
index 29b96dbb2c..a82ecf843d 100644
--- a/include/mbedtls/des.h
+++ b/include/mbedtls/des.h
@@ -147,6 +147,7 @@ void mbedtls_des_key_set_parity( unsigned char key[MBEDTLS_DES_KEY_SIZE] );
  *                 security risk. We recommend considering stronger ciphers
  *                 instead.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_des_key_check_key_parity( const unsigned char key[MBEDTLS_DES_KEY_SIZE] );
 
 /**
@@ -160,6 +161,7 @@ int mbedtls_des_key_check_key_parity( const unsigned char key[MBEDTLS_DES_KEY_SI
  *                 security risk. We recommend considering stronger ciphers
  *                 instead.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_des_key_check_weak( const unsigned char key[MBEDTLS_DES_KEY_SIZE] );
 
 /**
@@ -174,6 +176,7 @@ int mbedtls_des_key_check_weak( const unsigned char key[MBEDTLS_DES_KEY_SIZE] );
  *                 security risk. We recommend considering stronger ciphers
  *                 instead.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_des_setkey_enc( mbedtls_des_context *ctx, const unsigned char key[MBEDTLS_DES_KEY_SIZE] );
 
 /**
@@ -188,6 +191,7 @@ int mbedtls_des_setkey_enc( mbedtls_des_context *ctx, const unsigned char key[MB
  *                 security risk. We recommend considering stronger ciphers
  *                 instead.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_des_setkey_dec( mbedtls_des_context *ctx, const unsigned char key[MBEDTLS_DES_KEY_SIZE] );
 
 /**
@@ -198,6 +202,7 @@ int mbedtls_des_setkey_dec( mbedtls_des_context *ctx, const unsigned char key[MB
  *
  * \return         0
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_des3_set2key_enc( mbedtls_des3_context *ctx,
                       const unsigned char key[MBEDTLS_DES_KEY_SIZE * 2] );
 
@@ -209,6 +214,7 @@ int mbedtls_des3_set2key_enc( mbedtls_des3_context *ctx,
  *
  * \return         0
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_des3_set2key_dec( mbedtls_des3_context *ctx,
                       const unsigned char key[MBEDTLS_DES_KEY_SIZE * 2] );
 
@@ -220,6 +226,7 @@ int mbedtls_des3_set2key_dec( mbedtls_des3_context *ctx,
  *
  * \return         0
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_des3_set3key_enc( mbedtls_des3_context *ctx,
                       const unsigned char key[MBEDTLS_DES_KEY_SIZE * 3] );
 
@@ -231,6 +238,7 @@ int mbedtls_des3_set3key_enc( mbedtls_des3_context *ctx,
  *
  * \return         0
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_des3_set3key_dec( mbedtls_des3_context *ctx,
                       const unsigned char key[MBEDTLS_DES_KEY_SIZE * 3] );
 
@@ -247,6 +255,7 @@ int mbedtls_des3_set3key_dec( mbedtls_des3_context *ctx,
  *                 security risk. We recommend considering stronger ciphers
  *                 instead.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_des_crypt_ecb( mbedtls_des_context *ctx,
                     const unsigned char input[8],
                     unsigned char output[8] );
@@ -274,6 +283,7 @@ int mbedtls_des_crypt_ecb( mbedtls_des_context *ctx,
  *                 security risk. We recommend considering stronger ciphers
  *                 instead.
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_des_crypt_cbc( mbedtls_des_context *ctx,
                     int mode,
                     size_t length,
@@ -291,6 +301,7 @@ int mbedtls_des_crypt_cbc( mbedtls_des_context *ctx,
  *
  * \return         0 if successful
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_des3_crypt_ecb( mbedtls_des3_context *ctx,
                      const unsigned char input[8],
                      unsigned char output[8] );
@@ -316,6 +327,7 @@ int mbedtls_des3_crypt_ecb( mbedtls_des3_context *ctx,
  *
  * \return         0 if successful, or MBEDTLS_ERR_DES_INVALID_INPUT_LENGTH
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_des3_crypt_cbc( mbedtls_des3_context *ctx,
                      int mode,
                      size_t length,
@@ -346,6 +358,7 @@ void mbedtls_des_setkey( uint32_t SK[32],
  *
  * \return         0 if successful, or 1 if the test failed
  */
+MBEDTLS_CHECK_RETURN
 int mbedtls_des_self_test( int verbose );
 
 #endif /* MBEDTLS_SELF_TEST */
diff --git a/library/aes.c b/library/aes.c
index 3f616427ac..e4bcfa0237 100644
--- a/library/aes.c
+++ b/library/aes.c
@@ -1052,6 +1052,7 @@ int mbedtls_aes_crypt_cbc( mbedtls_aes_context *ctx,
                     unsigned char *output )
 {
     int i;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     unsigned char temp[16];
 
     AES_VALIDATE_RET( ctx != NULL );
@@ -1081,7 +1082,9 @@ int mbedtls_aes_crypt_cbc( mbedtls_aes_context *ctx,
         while( length > 0 )
         {
             memcpy( temp, input, 16 );
-            mbedtls_aes_crypt_ecb( ctx, mode, input, output );
+            ret = mbedtls_aes_crypt_ecb( ctx, mode, input, output );
+            if( ret != 0 )
+                goto exit;
 
             for( i = 0; i < 16; i++ )
                 output[i] = (unsigned char)( output[i] ^ iv[i] );
@@ -1100,7 +1103,9 @@ int mbedtls_aes_crypt_cbc( mbedtls_aes_context *ctx,
             for( i = 0; i < 16; i++ )
                 output[i] = (unsigned char)( input[i] ^ iv[i] );
 
-            mbedtls_aes_crypt_ecb( ctx, mode, output, output );
+            ret = mbedtls_aes_crypt_ecb( ctx, mode, output, output );
+            if( ret != 0 )
+                goto exit;
             memcpy( iv, output, 16 );
 
             input  += 16;
@@ -1108,8 +1113,10 @@ int mbedtls_aes_crypt_cbc( mbedtls_aes_context *ctx,
             length -= 16;
         }
     }
+    ret = 0;
 
-    return( 0 );
+exit:
+    return( ret );
 }
 #endif /* MBEDTLS_CIPHER_MODE_CBC */
 
@@ -1292,6 +1299,7 @@ int mbedtls_aes_crypt_cfb128( mbedtls_aes_context *ctx,
                        unsigned char *output )
 {
     int c;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     size_t n;
 
     AES_VALIDATE_RET( ctx != NULL );
@@ -1312,7 +1320,11 @@ int mbedtls_aes_crypt_cfb128( mbedtls_aes_context *ctx,
         while( length-- )
         {
             if( n == 0 )
-                mbedtls_aes_crypt_ecb( ctx, MBEDTLS_AES_ENCRYPT, iv, iv );
+            {
+                ret = mbedtls_aes_crypt_ecb( ctx, MBEDTLS_AES_ENCRYPT, iv, iv );
+                if( ret != 0 )
+                    goto exit;
+            }
 
             c = *input++;
             *output++ = (unsigned char)( c ^ iv[n] );
@@ -1326,7 +1338,11 @@ int mbedtls_aes_crypt_cfb128( mbedtls_aes_context *ctx,
         while( length-- )
         {
             if( n == 0 )
-                mbedtls_aes_crypt_ecb( ctx, MBEDTLS_AES_ENCRYPT, iv, iv );
+            {
+                ret = mbedtls_aes_crypt_ecb( ctx, MBEDTLS_AES_ENCRYPT, iv, iv );
+                if( ret != 0 )
+                    goto exit;
+            }
 
             iv[n] = *output++ = (unsigned char)( iv[n] ^ *input++ );
 
@@ -1335,8 +1351,10 @@ int mbedtls_aes_crypt_cfb128( mbedtls_aes_context *ctx,
     }
 
     *iv_off = n;
+    ret = 0;
 
-    return( 0 );
+exit:
+    return( ret );
 }
 
 /*
@@ -1349,6 +1367,7 @@ int mbedtls_aes_crypt_cfb8( mbedtls_aes_context *ctx,
                             const unsigned char *input,
                             unsigned char *output )
 {
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     unsigned char c;
     unsigned char ov[17];
 
@@ -1361,7 +1380,9 @@ int mbedtls_aes_crypt_cfb8( mbedtls_aes_context *ctx,
     while( length-- )
     {
         memcpy( ov, iv, 16 );
-        mbedtls_aes_crypt_ecb( ctx, MBEDTLS_AES_ENCRYPT, iv, iv );
+        ret = mbedtls_aes_crypt_ecb( ctx, MBEDTLS_AES_ENCRYPT, iv, iv );
+        if( ret != 0 )
+            goto exit;
 
         if( mode == MBEDTLS_AES_DECRYPT )
             ov[16] = *input;
@@ -1373,8 +1394,10 @@ int mbedtls_aes_crypt_cfb8( mbedtls_aes_context *ctx,
 
         memcpy( iv, ov + 1, 16 );
     }
+    ret = 0;
 
-    return( 0 );
+exit:
+    return( ret );
 }
 #endif /* MBEDTLS_CIPHER_MODE_CFB */
 
@@ -1436,6 +1459,7 @@ int mbedtls_aes_crypt_ctr( mbedtls_aes_context *ctx,
                        unsigned char *output )
 {
     int c, i;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     size_t n;
 
     AES_VALIDATE_RET( ctx != NULL );
@@ -1453,7 +1477,9 @@ int mbedtls_aes_crypt_ctr( mbedtls_aes_context *ctx,
     while( length-- )
     {
         if( n == 0 ) {
-            mbedtls_aes_crypt_ecb( ctx, MBEDTLS_AES_ENCRYPT, nonce_counter, stream_block );
+            ret = mbedtls_aes_crypt_ecb( ctx, MBEDTLS_AES_ENCRYPT, nonce_counter, stream_block );
+            if( ret != 0 )
+                goto exit;
 
             for( i = 16; i > 0; i-- )
                 if( ++nonce_counter[i - 1] != 0 )
@@ -1466,8 +1492,10 @@ int mbedtls_aes_crypt_ctr( mbedtls_aes_context *ctx,
     }
 
     *nc_off = n;
+    ret = 0;
 
-    return( 0 );
+exit:
+    return( ret );
 }
 #endif /* MBEDTLS_CIPHER_MODE_CTR */
 
diff --git a/library/des.c b/library/des.c
index eddf55e789..9ff4190462 100644
--- a/library/des.c
+++ b/library/des.c
@@ -28,6 +28,7 @@
 #if defined(MBEDTLS_DES_C)
 
 #include "mbedtls/des.h"
+#include "mbedtls/error.h"
 #include "mbedtls/platform_util.h"
 
 #include <string.h>
@@ -665,6 +666,7 @@ int mbedtls_des_crypt_cbc( mbedtls_des_context *ctx,
                     unsigned char *output )
 {
     int i;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     unsigned char temp[8];
 
     if( length % 8 )
@@ -677,7 +679,9 @@ int mbedtls_des_crypt_cbc( mbedtls_des_context *ctx,
             for( i = 0; i < 8; i++ )
                 output[i] = (unsigned char)( input[i] ^ iv[i] );
 
-            mbedtls_des_crypt_ecb( ctx, output, output );
+            ret = mbedtls_des_crypt_ecb( ctx, output, output );
+            if( ret != 0 )
+                goto exit;
             memcpy( iv, output, 8 );
 
             input  += 8;
@@ -690,7 +694,9 @@ int mbedtls_des_crypt_cbc( mbedtls_des_context *ctx,
         while( length > 0 )
         {
             memcpy( temp, input, 8 );
-            mbedtls_des_crypt_ecb( ctx, input, output );
+            ret = mbedtls_des_crypt_ecb( ctx, input, output );
+            if( ret != 0 )
+                goto exit;
 
             for( i = 0; i < 8; i++ )
                 output[i] = (unsigned char)( output[i] ^ iv[i] );
@@ -702,8 +708,10 @@ int mbedtls_des_crypt_cbc( mbedtls_des_context *ctx,
             length -= 8;
         }
     }
+    ret = 0;
 
-    return( 0 );
+exit:
+    return( ret );
 }
 #endif /* MBEDTLS_CIPHER_MODE_CBC */
 
@@ -764,6 +772,7 @@ int mbedtls_des3_crypt_cbc( mbedtls_des3_context *ctx,
                      unsigned char *output )
 {
     int i;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     unsigned char temp[8];
 
     if( length % 8 )
@@ -776,7 +785,9 @@ int mbedtls_des3_crypt_cbc( mbedtls_des3_context *ctx,
             for( i = 0; i < 8; i++ )
                 output[i] = (unsigned char)( input[i] ^ iv[i] );
 
-            mbedtls_des3_crypt_ecb( ctx, output, output );
+            ret = mbedtls_des3_crypt_ecb( ctx, output, output );
+            if( ret != 0 )
+                goto exit;
             memcpy( iv, output, 8 );
 
             input  += 8;
@@ -789,7 +800,9 @@ int mbedtls_des3_crypt_cbc( mbedtls_des3_context *ctx,
         while( length > 0 )
         {
             memcpy( temp, input, 8 );
-            mbedtls_des3_crypt_ecb( ctx, input, output );
+            ret = mbedtls_des3_crypt_ecb( ctx, input, output );
+            if( ret != 0 )
+                goto exit;
 
             for( i = 0; i < 8; i++ )
                 output[i] = (unsigned char)( output[i] ^ iv[i] );
@@ -801,8 +814,10 @@ int mbedtls_des3_crypt_cbc( mbedtls_des3_context *ctx,
             length -= 8;
         }
     }
+    ret = 0;
 
-    return( 0 );
+exit:
+    return( ret );
 }
 #endif /* MBEDTLS_CIPHER_MODE_CBC */
 
@@ -895,39 +910,43 @@ int mbedtls_des_self_test( int verbose )
         switch( i )
         {
         case 0:
-            mbedtls_des_setkey_dec( &ctx, des3_test_keys );
+            ret = mbedtls_des_setkey_dec( &ctx, des3_test_keys );
             break;
 
         case 1:
-            mbedtls_des_setkey_enc( &ctx, des3_test_keys );
+            ret = mbedtls_des_setkey_enc( &ctx, des3_test_keys );
             break;
 
         case 2:
-            mbedtls_des3_set2key_dec( &ctx3, des3_test_keys );
+            ret = mbedtls_des3_set2key_dec( &ctx3, des3_test_keys );
             break;
 
         case 3:
-            mbedtls_des3_set2key_enc( &ctx3, des3_test_keys );
+            ret = mbedtls_des3_set2key_enc( &ctx3, des3_test_keys );
             break;
 
         case 4:
-            mbedtls_des3_set3key_dec( &ctx3, des3_test_keys );
+            ret = mbedtls_des3_set3key_dec( &ctx3, des3_test_keys );
             break;
 
         case 5:
-            mbedtls_des3_set3key_enc( &ctx3, des3_test_keys );
+            ret = mbedtls_des3_set3key_enc( &ctx3, des3_test_keys );
             break;
 
         default:
             return( 1 );
         }
+        if( ret != 0 )
+            goto exit;
 
         for( j = 0; j < 100; j++ )
         {
             if( u == 0 )
-                mbedtls_des_crypt_ecb( &ctx, buf, buf );
+                ret = mbedtls_des_crypt_ecb( &ctx, buf, buf );
             else
-                mbedtls_des3_crypt_ecb( &ctx3, buf, buf );
+                ret = mbedtls_des3_crypt_ecb( &ctx3, buf, buf );
+            if( ret != 0 )
+                goto exit;
         }
 
         if( ( v == MBEDTLS_DES_DECRYPT &&
@@ -970,41 +989,45 @@ int mbedtls_des_self_test( int verbose )
         switch( i )
         {
         case 0:
-            mbedtls_des_setkey_dec( &ctx, des3_test_keys );
+            ret = mbedtls_des_setkey_dec( &ctx, des3_test_keys );
             break;
 
         case 1:
-            mbedtls_des_setkey_enc( &ctx, des3_test_keys );
+            ret = mbedtls_des_setkey_enc( &ctx, des3_test_keys );
             break;
 
         case 2:
-            mbedtls_des3_set2key_dec( &ctx3, des3_test_keys );
+            ret = mbedtls_des3_set2key_dec( &ctx3, des3_test_keys );
             break;
 
         case 3:
-            mbedtls_des3_set2key_enc( &ctx3, des3_test_keys );
+            ret = mbedtls_des3_set2key_enc( &ctx3, des3_test_keys );
             break;
 
         case 4:
-            mbedtls_des3_set3key_dec( &ctx3, des3_test_keys );
+            ret = mbedtls_des3_set3key_dec( &ctx3, des3_test_keys );
             break;
 
         case 5:
-            mbedtls_des3_set3key_enc( &ctx3, des3_test_keys );
+            ret = mbedtls_des3_set3key_enc( &ctx3, des3_test_keys );
             break;
 
         default:
             return( 1 );
         }
+        if( ret != 0 )
+            goto exit;
 
         if( v == MBEDTLS_DES_DECRYPT )
         {
             for( j = 0; j < 100; j++ )
             {
                 if( u == 0 )
-                    mbedtls_des_crypt_cbc( &ctx, v, 8, iv, buf, buf );
+                    ret = mbedtls_des_crypt_cbc( &ctx, v, 8, iv, buf, buf );
                 else
-                    mbedtls_des3_crypt_cbc( &ctx3, v, 8, iv, buf, buf );
+                    ret = mbedtls_des3_crypt_cbc( &ctx3, v, 8, iv, buf, buf );
+                if( ret != 0 )
+                    goto exit;
             }
         }
         else
@@ -1014,9 +1037,11 @@ int mbedtls_des_self_test( int verbose )
                 unsigned char tmp[8];
 
                 if( u == 0 )
-                    mbedtls_des_crypt_cbc( &ctx, v, 8, iv, buf, buf );
+                    ret = mbedtls_des_crypt_cbc( &ctx, v, 8, iv, buf, buf );
                 else
-                    mbedtls_des3_crypt_cbc( &ctx3, v, 8, iv, buf, buf );
+                    ret = mbedtls_des3_crypt_cbc( &ctx3, v, 8, iv, buf, buf );
+                if( ret != 0 )
+                    goto exit;
 
                 memcpy( tmp, prv, 8 );
                 memcpy( prv, buf, 8 );
@@ -1050,6 +1075,8 @@ exit:
     mbedtls_des_free( &ctx );
     mbedtls_des3_free( &ctx3 );
 
+    if( ret != 0 )
+        ret = 1;
     return( ret );
 }
 
diff --git a/programs/pkey/dh_client.c b/programs/pkey/dh_client.c
index d6e4990a9b..f6c622608e 100644
--- a/programs/pkey/dh_client.c
+++ b/programs/pkey/dh_client.c
@@ -274,7 +274,9 @@ int main( void )
     mbedtls_printf( "...\n  . Receiving and decrypting the ciphertext" );
     fflush( stdout );
 
-    mbedtls_aes_setkey_dec( &aes, buf, 256 );
+    ret = mbedtls_aes_setkey_dec( &aes, buf, 256 );
+    if( ret != 0 )
+        goto exit;
 
     memset( buf, 0, sizeof( buf ) );
 
@@ -284,7 +286,9 @@ int main( void )
         goto exit;
     }
 
-    mbedtls_aes_crypt_ecb( &aes, MBEDTLS_AES_DECRYPT, buf, buf );
+    ret = mbedtls_aes_crypt_ecb( &aes, MBEDTLS_AES_DECRYPT, buf, buf );
+    if( ret != 0 )
+        goto exit;
     buf[16] = '\0';
     mbedtls_printf( "\n  . Plaintext is \"%s\"\n\n", (char *) buf );
 
diff --git a/programs/pkey/dh_server.c b/programs/pkey/dh_server.c
index dccf0951ca..8f032a3b20 100644
--- a/programs/pkey/dh_server.c
+++ b/programs/pkey/dh_server.c
@@ -295,9 +295,13 @@ int main( void )
     mbedtls_printf( "...\n  . Encrypting and sending the ciphertext" );
     fflush( stdout );
 
-    mbedtls_aes_setkey_enc( &aes, buf, 256 );
+    ret = mbedtls_aes_setkey_enc( &aes, buf, 256 );
+    if( ret != 0 )
+        goto exit;
     memcpy( buf, PLAINTEXT, 16 );
-    mbedtls_aes_crypt_ecb( &aes, MBEDTLS_AES_ENCRYPT, buf, buf );
+    ret = mbedtls_aes_crypt_ecb( &aes, MBEDTLS_AES_ENCRYPT, buf, buf );
+    if( ret != 0 )
+        goto exit;
 
     if( ( ret = mbedtls_net_send( &client_fd, buf, 16 ) ) != 16 )
     {
diff --git a/programs/test/benchmark.c b/programs/test/benchmark.c
index 9c5911ba29..88c9e65c53 100644
--- a/programs/test/benchmark.c
+++ b/programs/test/benchmark.c
@@ -449,7 +449,8 @@ int main( int argc, char *argv[] )
     {
         mbedtls_des3_context des3;
         mbedtls_des3_init( &des3 );
-        mbedtls_des3_set3key_enc( &des3, tmp );
+        if( mbedtls_des3_set3key_enc( &des3, tmp ) != 0 )
+            mbedtls_exit( 1 );
         TIME_AND_TSC( "3DES",
                 mbedtls_des3_crypt_cbc( &des3, MBEDTLS_DES_ENCRYPT, BUFSIZE, tmp, buf, buf ) );
         mbedtls_des3_free( &des3 );
@@ -459,7 +460,8 @@ int main( int argc, char *argv[] )
     {
         mbedtls_des_context des;
         mbedtls_des_init( &des );
-        mbedtls_des_setkey_enc( &des, tmp );
+        if( mbedtls_des_setkey_enc( &des, tmp ) != 0 )
+            mbedtls_exit( 1 );
         TIME_AND_TSC( "DES",
                 mbedtls_des_crypt_cbc( &des, MBEDTLS_DES_ENCRYPT, BUFSIZE, tmp, buf, buf ) );
         mbedtls_des_free( &des );
@@ -497,7 +499,7 @@ int main( int argc, char *argv[] )
 
             memset( buf, 0, sizeof( buf ) );
             memset( tmp, 0, sizeof( tmp ) );
-            mbedtls_aes_setkey_enc( &aes, tmp, keysize );
+            CHECK_AND_CONTINUE( mbedtls_aes_setkey_enc( &aes, tmp, keysize ) );
 
             TIME_AND_TSC( title,
                 mbedtls_aes_crypt_cbc( &aes, MBEDTLS_AES_ENCRYPT, BUFSIZE, tmp, buf, buf ) );
@@ -518,7 +520,7 @@ int main( int argc, char *argv[] )
 
             memset( buf, 0, sizeof( buf ) );
             memset( tmp, 0, sizeof( tmp ) );
-            mbedtls_aes_xts_setkey_enc( &ctx, tmp, keysize * 2 );
+            CHECK_AND_CONTINUE( mbedtls_aes_xts_setkey_enc( &ctx, tmp, keysize * 2 ) );
 
             TIME_AND_TSC( title,
                     mbedtls_aes_crypt_xts( &ctx, MBEDTLS_AES_ENCRYPT, BUFSIZE,
diff --git a/tests/suites/test_suite_aes.function b/tests/suites/test_suite_aes.function
index a90277d970..5a64099fb4 100644
--- a/tests/suites/test_suite_aes.function
+++ b/tests/suites/test_suite_aes.function
@@ -67,7 +67,7 @@ void aes_encrypt_cbc( data_t * key_str, data_t * iv_str,
 
     mbedtls_aes_init( &ctx );
 
-    mbedtls_aes_setkey_enc( &ctx, key_str->x, key_str->len * 8 );
+    TEST_ASSERT( mbedtls_aes_setkey_enc( &ctx, key_str->x, key_str->len * 8 ) == 0 );
     TEST_ASSERT( mbedtls_aes_crypt_cbc( &ctx, MBEDTLS_AES_ENCRYPT, src_str->len, iv_str->x, src_str->x, output ) == cbc_result );
     if( cbc_result == 0 )
     {
@@ -92,7 +92,7 @@ void aes_decrypt_cbc( data_t * key_str, data_t * iv_str,
     memset(output, 0x00, 100);
     mbedtls_aes_init( &ctx );
 
-    mbedtls_aes_setkey_dec( &ctx, key_str->x, key_str->len * 8 );
+    TEST_ASSERT( mbedtls_aes_setkey_dec( &ctx, key_str->x, key_str->len * 8 ) == 0 );
     TEST_ASSERT( mbedtls_aes_crypt_cbc( &ctx, MBEDTLS_AES_DECRYPT, src_str->len, iv_str->x, src_str->x, output ) == cbc_result );
     if( cbc_result == 0)
     {
@@ -244,7 +244,7 @@ void aes_encrypt_cfb128( data_t * key_str, data_t * iv_str,
     mbedtls_aes_init( &ctx );
 
 
-    mbedtls_aes_setkey_enc( &ctx, key_str->x, key_str->len * 8 );
+    TEST_ASSERT( mbedtls_aes_setkey_enc( &ctx, key_str->x, key_str->len * 8 ) == 0 );
     TEST_ASSERT( mbedtls_aes_crypt_cfb128( &ctx, MBEDTLS_AES_ENCRYPT, 16, &iv_offset, iv_str->x, src_str->x, output ) == 0 );
 
     TEST_ASSERT( mbedtls_test_hexcmp( output, dst->x, 16, dst->len ) == 0 );
@@ -266,7 +266,7 @@ void aes_decrypt_cfb128( data_t * key_str, data_t * iv_str,
     mbedtls_aes_init( &ctx );
 
 
-    mbedtls_aes_setkey_enc( &ctx, key_str->x, key_str->len * 8 );
+    TEST_ASSERT( mbedtls_aes_setkey_enc( &ctx, key_str->x, key_str->len * 8 ) == 0 );
     TEST_ASSERT( mbedtls_aes_crypt_cfb128( &ctx, MBEDTLS_AES_DECRYPT, 16, &iv_offset, iv_str->x, src_str->x, output ) == 0 );
 
     TEST_ASSERT( mbedtls_test_hexcmp( output, dst->x, 16, dst->len ) == 0 );
@@ -287,7 +287,7 @@ void aes_encrypt_cfb8( data_t * key_str, data_t * iv_str,
     mbedtls_aes_init( &ctx );
 
 
-    mbedtls_aes_setkey_enc( &ctx, key_str->x, key_str->len * 8 );
+    TEST_ASSERT( mbedtls_aes_setkey_enc( &ctx, key_str->x, key_str->len * 8 ) == 0 );
     TEST_ASSERT( mbedtls_aes_crypt_cfb8( &ctx, MBEDTLS_AES_ENCRYPT, src_str->len, iv_str->x, src_str->x, output ) == 0 );
 
     TEST_ASSERT( mbedtls_test_hexcmp( output, dst->x,
@@ -309,7 +309,7 @@ void aes_decrypt_cfb8( data_t * key_str, data_t * iv_str,
     mbedtls_aes_init( &ctx );
 
 
-    mbedtls_aes_setkey_enc( &ctx, key_str->x, key_str->len * 8 );
+    TEST_ASSERT( mbedtls_aes_setkey_enc( &ctx, key_str->x, key_str->len * 8 ) == 0 );
     TEST_ASSERT( mbedtls_aes_crypt_cfb8( &ctx, MBEDTLS_AES_DECRYPT, src_str->len, iv_str->x, src_str->x, output ) == 0 );
 
     TEST_ASSERT( mbedtls_test_hexcmp( output, dst->x,
diff --git a/tests/suites/test_suite_des.function b/tests/suites/test_suite_des.function
index 5b249355b6..7256fb5376 100644
--- a/tests/suites/test_suite_des.function
+++ b/tests/suites/test_suite_des.function
@@ -24,7 +24,7 @@ void des_encrypt_ecb( data_t * key_str, data_t * src_str, data_t * dst )
     mbedtls_des_init( &ctx );
 
 
-    mbedtls_des_setkey_enc( &ctx, key_str->x );
+    TEST_ASSERT( mbedtls_des_setkey_enc( &ctx, key_str->x ) == 0 );
     TEST_ASSERT( mbedtls_des_crypt_ecb( &ctx, src_str->x, output ) == 0 );
 
     TEST_ASSERT( mbedtls_test_hexcmp( output, dst->x, 8, dst->len ) == 0 );
@@ -44,7 +44,7 @@ void des_decrypt_ecb( data_t * key_str, data_t * src_str, data_t * dst )
     mbedtls_des_init( &ctx );
 
 
-    mbedtls_des_setkey_dec( &ctx, key_str->x );
+    TEST_ASSERT( mbedtls_des_setkey_dec( &ctx, key_str->x ) == 0 );
     TEST_ASSERT( mbedtls_des_crypt_ecb( &ctx, src_str->x, output ) == 0 );
 
     TEST_ASSERT( mbedtls_test_hexcmp( output, dst->x, 8, dst->len ) == 0 );
@@ -65,7 +65,7 @@ void des_encrypt_cbc( data_t * key_str, data_t * iv_str,
     mbedtls_des_init( &ctx );
 
 
-    mbedtls_des_setkey_enc( &ctx, key_str->x );
+    TEST_ASSERT( mbedtls_des_setkey_enc( &ctx, key_str->x ) == 0 );
     TEST_ASSERT( mbedtls_des_crypt_cbc( &ctx, MBEDTLS_DES_ENCRYPT, src_str->len, iv_str->x, src_str->x, output ) == cbc_result );
     if( cbc_result == 0 )
     {
@@ -91,7 +91,7 @@ void des_decrypt_cbc( data_t * key_str, data_t * iv_str,
     mbedtls_des_init( &ctx );
 
 
-    mbedtls_des_setkey_dec( &ctx, key_str->x );
+    TEST_ASSERT( mbedtls_des_setkey_dec( &ctx, key_str->x ) == 0 );
     TEST_ASSERT( mbedtls_des_crypt_cbc( &ctx, MBEDTLS_DES_DECRYPT, src_str->len, iv_str->x, src_str->x, output ) == cbc_result );
     if( cbc_result == 0 )
     {
@@ -117,9 +117,9 @@ void des3_encrypt_ecb( int key_count, data_t * key_str,
 
 
     if( key_count == 2 )
-        mbedtls_des3_set2key_enc( &ctx, key_str->x );
+        TEST_ASSERT( mbedtls_des3_set2key_enc( &ctx, key_str->x ) == 0 );
     else if( key_count == 3 )
-        mbedtls_des3_set3key_enc( &ctx, key_str->x );
+        TEST_ASSERT( mbedtls_des3_set3key_enc( &ctx, key_str->x ) == 0 );
     else
         TEST_ASSERT( 0 );
 
@@ -144,9 +144,9 @@ void des3_decrypt_ecb( int key_count, data_t * key_str,
 
 
     if( key_count == 2 )
-        mbedtls_des3_set2key_dec( &ctx, key_str->x );
+        TEST_ASSERT( mbedtls_des3_set2key_dec( &ctx, key_str->x ) == 0 );
     else if( key_count == 3 )
-        mbedtls_des3_set3key_dec( &ctx, key_str->x );
+        TEST_ASSERT( mbedtls_des3_set3key_dec( &ctx, key_str->x ) == 0 );
     else
         TEST_ASSERT( 0 );
 
@@ -172,9 +172,9 @@ void des3_encrypt_cbc( int key_count, data_t * key_str,
 
 
     if( key_count == 2 )
-        mbedtls_des3_set2key_enc( &ctx, key_str->x );
+        TEST_ASSERT( mbedtls_des3_set2key_enc( &ctx, key_str->x ) == 0 );
     else if( key_count == 3 )
-        mbedtls_des3_set3key_enc( &ctx, key_str->x );
+        TEST_ASSERT( mbedtls_des3_set3key_enc( &ctx, key_str->x ) == 0 );
     else
         TEST_ASSERT( 0 );
 
@@ -205,9 +205,9 @@ void des3_decrypt_cbc( int key_count, data_t * key_str,
 
 
     if( key_count == 2 )
-        mbedtls_des3_set2key_dec( &ctx, key_str->x );
+        TEST_ASSERT( mbedtls_des3_set2key_dec( &ctx, key_str->x ) == 0 );
     else if( key_count == 3 )
-        mbedtls_des3_set3key_dec( &ctx, key_str->x );
+        TEST_ASSERT( mbedtls_des3_set3key_dec( &ctx, key_str->x ) == 0 );
     else
         TEST_ASSERT( 0 );