diff --git a/tests/suites/test_suite_aes.function b/tests/suites/test_suite_aes.function
index f1be3cec2..d5eb1ef10 100644
--- a/tests/suites/test_suite_aes.function
+++ b/tests/suites/test_suite_aes.function
@@ -329,13 +329,13 @@ exit:
 /* BEGIN_CASE depends_on:MBEDTLS_CIPHER_MODE_OFB */
 void aes_encrypt_ofb( int fragment_size, char *hex_key_string,
                       char *hex_iv_string, char *hex_src_string,
-                      char *hex_dst_string )
+                      char *hex_expected_output_string )
 {
     unsigned char key_str[32];
     unsigned char iv_str[16];
     unsigned char src_str[64];
-    unsigned char dst_str[64];
     unsigned char output[32];
+    unsigned char output_string[65];
     mbedtls_aes_context ctx;
     size_t iv_offset = 0;
     int in_buffer_len;
@@ -345,14 +345,15 @@ void aes_encrypt_ofb( int fragment_size, char *hex_key_string,
     memset( key_str, 0x00, sizeof( key_str ) );
     memset( iv_str, 0x00, sizeof( iv_str ) );
     memset( src_str, 0x00, sizeof( src_str ) );
-    memset( dst_str, 0x00, sizeof( dst_str ) );
     memset( output, 0x00, sizeof( output ) );
+    memset( output_string, 0x00, sizeof( output_string ) );
     mbedtls_aes_init( &ctx );
 
+    TEST_ASSERT( (size_t)fragment_size < sizeof( output ) );
     TEST_ASSERT( strlen( hex_key_string ) <= ( 32 * 2 ) );
     TEST_ASSERT( strlen( hex_iv_string ) <= ( 16 * 2 ) );
     TEST_ASSERT( strlen( hex_src_string ) <= ( 64 * 2 ) );
-    TEST_ASSERT( strlen( hex_dst_string ) <= ( 64 * 2 ) );
+    TEST_ASSERT( strlen( hex_expected_output_string ) <= ( 64 * 2 ) );
 
     key_len = mbedtls_test_unhexify( key_str, hex_key_string );
     mbedtls_test_unhexify( iv_str, hex_iv_string );
@@ -366,12 +367,12 @@ void aes_encrypt_ofb( int fragment_size, char *hex_key_string,
         TEST_ASSERT( mbedtls_aes_crypt_ofb( &ctx, fragment_size, &iv_offset,
                                             iv_str, src_str_next, output ) == 0 );
 
-        mbedtls_test_hexify( dst_str, output, fragment_size );
-        TEST_ASSERT( strncmp( (char *) dst_str, hex_dst_string,
+        mbedtls_test_hexify( output_string, output, fragment_size );
+        TEST_ASSERT( strncmp( (char *) output_string, hex_expected_output_string,
                               ( 2 * fragment_size ) ) == 0 );
 
         in_buffer_len -= fragment_size;
-        hex_dst_string += ( fragment_size * 2 );
+        hex_expected_output_string += ( fragment_size * 2 );
         src_str_next += fragment_size;
 
         if( in_buffer_len < fragment_size )