diff --git a/tests/suites/helpers.function b/tests/suites/helpers.function
index 8e7f60d..f30f5e6 100644
--- a/tests/suites/helpers.function
+++ b/tests/suites/helpers.function
@@ -108,6 +108,27 @@
        }                                                    \
     } while( 0 )
 
+/** Compare two buffers and fail the test case if they differ.
+ *
+ * This macro expands to an instruction, not an expression.
+ * It may jump to the \c exit label.
+ *
+ * \param p1        Pointer to the start of the first buffer.
+ * \param size1     Size of the first buffer in bytes.
+ *                  This expression may be evaluated multiple times.
+ * \param p2        Pointer to the start of the second buffer.
+ * \param size2     Size of the second buffer in bytes.
+ *                  This expression may be evaluated multiple times.
+ */
+#define ASSERT_COMPARE( p1, size1, p2, size2 )                          \
+    do                                                                  \
+    {                                                                   \
+        TEST_ASSERT( ( size1 ) == ( size2 ) );                          \
+        if( ( size1 ) != 0 )                                            \
+            TEST_ASSERT( memcmp( ( p1 ), ( p2 ), ( size1 ) ) == 0 );    \
+    }                                                                   \
+    while( 0 )
+
 /**
  * \brief   This macro tests the expression passed to it and skips the
  *          running test if it doesn't evaluate to 'true'.
diff --git a/tests/suites/test_suite_aria.function b/tests/suites/test_suite_aria.function
index 3cc683b..6d6a203 100644
--- a/tests/suites/test_suite_aria.function
+++ b/tests/suites/test_suite_aria.function
@@ -226,8 +226,8 @@
                                                  output + i ) == 0 );
         }
 
-        TEST_ASSERT( !memcmp( output,
-                              expected_output->x, expected_output->len) );
+        ASSERT_COMPARE( output, expected_output->len,
+                        expected_output->x, expected_output->len );
     }
 
 exit:
@@ -256,8 +256,8 @@
                                                  output + i ) == 0 );
         }
 
-        TEST_ASSERT( !memcmp( output,
-                              expected_output->x, expected_output->len) );
+        ASSERT_COMPARE( output, expected_output->len,
+                        expected_output->x, expected_output->len );
     }
 
 exit:
@@ -282,8 +282,8 @@
                                          output ) == cbc_result );
     if( cbc_result == 0 )
     {
-        TEST_ASSERT( !memcmp( output,
-                              expected_output->x, expected_output->len) );
+        ASSERT_COMPARE( output, expected_output->len,
+                        expected_output->x, expected_output->len );
     }
 
 exit:
@@ -308,8 +308,8 @@
                                          output ) == cbc_result );
     if( cbc_result == 0 )
     {
-        TEST_ASSERT( !memcmp( output,
-                              expected_output->x, expected_output->len) );
+        ASSERT_COMPARE( output, expected_output->len,
+                        expected_output->x, expected_output->len );
     }
 
 exit:
@@ -335,7 +335,8 @@
                                             iv_str->x, src_str->x, output )
                  == result );
 
-    TEST_ASSERT( !memcmp( output, expected_output->x, expected_output->len) );
+    ASSERT_COMPARE( output, expected_output->len,
+                    expected_output->x, expected_output->len );
 
 exit:
     mbedtls_aria_free( &ctx );
@@ -360,7 +361,8 @@
                                             iv_str->x, src_str->x, output )
                  == result );
 
-    TEST_ASSERT( !memcmp( output, expected_output->x, expected_output->len) );
+    ASSERT_COMPARE( output, expected_output->len,
+                    expected_output->x, expected_output->len );
 
 exit:
     mbedtls_aria_free( &ctx );
@@ -385,7 +387,8 @@
                                          iv_str->x, blk, src_str->x, output )
                  == result );
 
-    TEST_ASSERT( !memcmp( output, expected_output->x, expected_output->len) );
+    ASSERT_COMPARE( output, expected_output->len,
+                    expected_output->x, expected_output->len );
 
 exit:
     mbedtls_aria_free( &ctx );
@@ -410,7 +413,8 @@
                                          iv_str->x, blk, src_str->x, output )
                  == result );
 
-    TEST_ASSERT( !memcmp( output, expected_output->x, expected_output->len) );
+    ASSERT_COMPARE( output, expected_output->len,
+                    expected_output->x, expected_output->len );
 
 exit:
     mbedtls_aria_free( &ctx );
diff --git a/tests/suites/test_suite_chacha20.function b/tests/suites/test_suite_chacha20.function
index 968a9e9..67c8de2 100644
--- a/tests/suites/test_suite_chacha20.function
+++ b/tests/suites/test_suite_chacha20.function
@@ -28,8 +28,8 @@
      */
     TEST_ASSERT( mbedtls_chacha20_crypt( key_str->x, nonce_str->x, counter, src_str->len, src_str->x, output ) == 0 );
 
-    TEST_ASSERT( !memcmp( output, expected_output_str->x,
-                          expected_output_str->len ) );
+    ASSERT_COMPARE( output, expected_output_str->len,
+                    expected_output_str->x, expected_output_str->len );
 
     /*
      * Test the streaming API
@@ -43,8 +43,8 @@
     memset( output, 0x00, sizeof( output ) );
     TEST_ASSERT( mbedtls_chacha20_update( &ctx, src_str->len, src_str->x, output ) == 0 );
 
-    TEST_ASSERT( !memcmp( output, expected_output_str->x,
-                          expected_output_str->len ) );
+    ASSERT_COMPARE( output, expected_output_str->len,
+                    expected_output_str->x, expected_output_str->len );
 
     /*
      * Test the streaming API again, piecewise
@@ -59,8 +59,8 @@
     TEST_ASSERT( mbedtls_chacha20_update( &ctx, src_str->len - 1,
                                           src_str->x + 1, output + 1 ) == 0 );
 
-    TEST_ASSERT( !memcmp( output, expected_output_str->x,
-                          expected_output_str->len ) );
+    ASSERT_COMPARE( output, expected_output_str->len,
+                    expected_output_str->x, expected_output_str->len );
 
     mbedtls_chacha20_free( &ctx );
 }
diff --git a/tests/suites/test_suite_hkdf.function b/tests/suites/test_suite_hkdf.function
index eca10af..af871e1 100644
--- a/tests/suites/test_suite_hkdf.function
+++ b/tests/suites/test_suite_hkdf.function
@@ -24,7 +24,8 @@
                         info->x, info->len, okm, expected_okm->len );
     TEST_ASSERT( ret == 0 );
 
-    TEST_ASSERT( !memcmp( okm, expected_okm->x, expected_okm->len ) );
+    ASSERT_COMPARE( okm            , expected_okm->len,
+                    expected_okm->x, expected_okm->len );
 }
 /* END_CASE */
 
@@ -48,12 +49,11 @@
     ikm = unhexify_alloc( hex_ikm_string, &ikm_len );
     salt = unhexify_alloc( hex_salt_string, &salt_len );
     prk = unhexify_alloc( hex_prk_string, &prk_len );
-    TEST_ASSERT( prk_len == output_prk_len );
 
     ret = mbedtls_hkdf_extract( md, salt, salt_len, ikm, ikm_len, output_prk );
     TEST_ASSERT( ret == 0 );
 
-    TEST_ASSERT( !memcmp( output_prk, prk, prk_len ) );
+    ASSERT_COMPARE( output_prk, output_prk_len, prk, prk_len );
 
 exit:
     mbedtls_free(ikm);
@@ -89,7 +89,7 @@
     ret = mbedtls_hkdf_expand( md, prk, prk_len, info, info_len,
                                output_okm, OKM_LEN );
     TEST_ASSERT( ret == 0 );
-    TEST_ASSERT( !memcmp( output_okm, okm, okm_len ) );
+    ASSERT_COMPARE( output_okm, okm_len, okm, okm_len );
 
 exit:
     mbedtls_free(info);
diff --git a/tests/suites/test_suite_poly1305.function b/tests/suites/test_suite_poly1305.function
index 0fc1f60..4b8995b 100644
--- a/tests/suites/test_suite_poly1305.function
+++ b/tests/suites/test_suite_poly1305.function
@@ -22,7 +22,8 @@
     TEST_ASSERT( mbedtls_poly1305_mac( key->x, src_str->x,
                                        src_str->len, mac ) == 0 );
 
-    TEST_ASSERT( !memcmp( mac, expected_mac->x, expected_mac->len ) );
+    ASSERT_COMPARE( mac, expected_mac->len,
+                    expected_mac->x, expected_mac->len );
 
     /*
      * Test the streaming API
@@ -35,7 +36,8 @@
 
     TEST_ASSERT( mbedtls_poly1305_finish( &ctx, mac ) == 0 );
 
-    TEST_ASSERT( !memcmp( mac, expected_mac->x, expected_mac->len ) );
+    ASSERT_COMPARE( mac, expected_mac->len,
+                    expected_mac->x, expected_mac->len );
 
     /*
      * Test the streaming API again, piecewise
@@ -52,7 +54,8 @@
 
         TEST_ASSERT( mbedtls_poly1305_finish( &ctx, mac ) == 0 );
 
-        TEST_ASSERT( !memcmp( mac, expected_mac->x, expected_mac->len ) );
+        ASSERT_COMPARE( mac, expected_mac->len,
+                        expected_mac->x, expected_mac->len );
     }
 
     /*
@@ -68,7 +71,8 @@
 
         TEST_ASSERT( mbedtls_poly1305_finish( &ctx, mac ) == 0 );
 
-        TEST_ASSERT( !memcmp( mac, expected_mac->x, expected_mac->len ) );
+        ASSERT_COMPARE( mac, expected_mac->len,
+                        expected_mac->x, expected_mac->len );
     }
 
     mbedtls_poly1305_free( &ctx );