diff --git a/tests/suites/test_suite_common.function b/tests/suites/test_suite_common.function
index 17eae27c4b..8412e60f3b 100644
--- a/tests/suites/test_suite_common.function
+++ b/tests/suites/test_suite_common.function
@@ -18,10 +18,10 @@ void mbedtls_xor( int len )
 {
     size_t n = (size_t) len;
     unsigned char *a = NULL, *b = NULL, *r1 = NULL, *r2 = NULL;
-    ASSERT_ALLOC( a, n );
-    ASSERT_ALLOC( b, n );
-    ASSERT_ALLOC( r1, n );
-    ASSERT_ALLOC( r2, n );
+    ASSERT_ALLOC( a, n + 1 );
+    ASSERT_ALLOC( b, n + 1 );
+    ASSERT_ALLOC( r1, n + 1 );
+    ASSERT_ALLOC( r2, n + 1 );
 
     /* Test non-overlapping */
     fill_arrays( a, b, r1, r2, n );
@@ -67,6 +67,15 @@ void mbedtls_xor( int len )
     }
     mbedtls_xor( r2, r2, r2, n );
     ASSERT_COMPARE( r1, n, r2, n );
+
+    /* Test non-word-aligned buffers */
+    fill_arrays( a + 1, b + 1, r1 + 1, r2 + 1, n );
+    for ( size_t i = 0; i < n; i++ )
+    {
+        r1[i + 1] = a[i + 1] ^ b[i + 1];
+    }
+    mbedtls_xor( r2 + 1, a + 1, b + 1, n );
+    ASSERT_COMPARE( r1 + 1, n, r2 + 1, n );
 exit:
     if ( a != NULL ) mbedtls_free( a );
     if ( a != NULL ) mbedtls_free( b );