diff --git a/src/crypto.h b/src/crypto.h
index 7269c36e..8cf34f5b 100644
--- a/src/crypto.h
+++ b/src/crypto.h
@@ -113,4 +113,6 @@ int _libssh2_pub_priv_keyfile(LIBSSH2_SESSION *session,
                               const char *privatekey,
                               const char *passphrase);
 
+void _libssh2_init_aes_ctr(void);
+
 #endif
diff --git a/src/global.c b/src/global.c
index 9f54c353..409e8e85 100644
--- a/src/global.c
+++ b/src/global.c
@@ -46,6 +46,7 @@ libssh2_init(int flags)
 {
     if (_libssh2_initialized == 0 && !(flags & LIBSSH2_INIT_NO_CRYPTO)) {
         libssh2_crypto_init();
+        _libssh2_init_aes_ctr();
     }
 
     _libssh2_initialized++;
diff --git a/src/libgcrypt.c b/src/libgcrypt.c
index 8d1dcef0..c3be56c3 100644
--- a/src/libgcrypt.c
+++ b/src/libgcrypt.c
@@ -585,4 +585,8 @@ _libssh2_pub_priv_keyfile(LIBSSH2_SESSION *session,
                   libssh2_error */
 }
 
+void _libssh2_init_aes_ctr(void)
+{
+    /* no implementation */
+}
 #endif /* LIBSSH2_LIBGCRYPT */
diff --git a/src/openssl.c b/src/openssl.c
index 51023e89..5fec5110 100644
--- a/src/openssl.c
+++ b/src/openssl.c
@@ -317,8 +317,6 @@ aes_ctr_cleanup(EVP_CIPHER_CTX *ctx) /* cleanup ctx */
 static const EVP_CIPHER *
 make_ctr_evp (size_t keylen, EVP_CIPHER *aes_ctr_cipher)
 {
-    memset(aes_ctr_cipher, 0, sizeof(aes_ctr_cipher));
-
     aes_ctr_cipher->block_size = 16;
     aes_ctr_cipher->key_len = keylen;
     aes_ctr_cipher->iv_len = 16;
@@ -333,22 +331,33 @@ const EVP_CIPHER *
 _libssh2_EVP_aes_128_ctr(void)
 {
     static EVP_CIPHER aes_ctr_cipher;
-    return make_ctr_evp (16, &aes_ctr_cipher);
+    return !aes_ctr_cipher.key_len?
+        make_ctr_evp (16, &aes_ctr_cipher) : &aes_ctr_cipher;
 }
 
 const EVP_CIPHER *
 _libssh2_EVP_aes_192_ctr(void)
 {
     static EVP_CIPHER aes_ctr_cipher;
-    return make_ctr_evp (24, &aes_ctr_cipher);
+    return !aes_ctr_cipher.key_len?
+        make_ctr_evp (24, &aes_ctr_cipher) : &aes_ctr_cipher;
 }
 
 const EVP_CIPHER *
 _libssh2_EVP_aes_256_ctr(void)
 {
     static EVP_CIPHER aes_ctr_cipher;
-    return make_ctr_evp (32, &aes_ctr_cipher);
+    return !aes_ctr_cipher.key_len?
+        make_ctr_evp (32, &aes_ctr_cipher) : &aes_ctr_cipher;
 }
+
+void _libssh2_init_aes_ctr(void)
+{
+    _libssh2_EVP_aes_128_ctr();
+    _libssh2_EVP_aes_192_ctr();
+    _libssh2_EVP_aes_256_ctr();
+}
+
 #endif /* LIBSSH2_AES_CTR */
 
 /* TODO: Optionally call a passphrase callback specified by the