diff --git a/tests/src/helpers.c b/tests/src/helpers.c
index 4d3d53d..ec4d84e 100644
--- a/tests/src/helpers.c
+++ b/tests/src/helpers.c
@@ -95,6 +95,31 @@
     mbedtls_test_info.test = 0;
     mbedtls_test_info.line_no = 0;
     mbedtls_test_info.filename = 0;
+    memset( mbedtls_test_info.line1, 0, sizeof( mbedtls_test_info.line1 ) );
+    memset( mbedtls_test_info.line2, 0, sizeof( mbedtls_test_info.line2 ) );
+}
+
+int mbedtls_test_equal( const char *test, int line_no, const char* filename,
+                        unsigned long long value1, unsigned long long value2 )
+{
+    if( value1 == value2 )
+        return( 1 );
+    if( mbedtls_test_info.result == MBEDTLS_TEST_RESULT_FAILED )
+    {
+        /* We've already recorded the test as having failed. Don't
+         * overwrite any previous information about the failure. */
+        return( 0 );
+    }
+    mbedtls_test_fail( test, line_no, filename );
+    (void) mbedtls_snprintf( mbedtls_test_info.line1,
+                             sizeof( mbedtls_test_info.line1 ),
+                             "lhs = 0x%016llx = %lld",
+                             value1, (long long) value1 );
+    (void) mbedtls_snprintf( mbedtls_test_info.line2,
+                             sizeof( mbedtls_test_info.line2 ),
+                             "rhs = 0x%016llx = %lld",
+                             value2, (long long) value2 );
+    return( 0 );
 }
 
 int mbedtls_test_unhexify( unsigned char *obuf,
diff --git a/tests/src/psa_exercise_key.c b/tests/src/psa_exercise_key.c
index e4e55c9..923d2c1 100644
--- a/tests/src/psa_exercise_key.c
+++ b/tests/src/psa_exercise_key.c
@@ -663,7 +663,7 @@
         TEST_EQUAL( mbedtls_asn1_get_tag( &p, end, &len,
                                           MBEDTLS_ASN1_SEQUENCE |
                                           MBEDTLS_ASN1_CONSTRUCTED ), 0 );
-        TEST_EQUAL( p + len, end );
+        TEST_EQUAL( len, end - p );
         if( ! mbedtls_test_asn1_skip_integer( &p, end, 0, 0, 0 ) )
             goto exit;
         if( ! mbedtls_test_asn1_skip_integer( &p, end, bits, bits, 1 ) )
@@ -684,7 +684,7 @@
             goto exit;
         if( ! mbedtls_test_asn1_skip_integer( &p, end, 1, bits / 2 + 1, 0 ) )
             goto exit;
-        TEST_EQUAL( p, end );
+        TEST_EQUAL( p - end, 0 );
 
         TEST_ASSERT( exported_length <= PSA_EXPORT_KEY_PAIR_MAX_SIZE );
     }
@@ -716,12 +716,12 @@
                                           MBEDTLS_ASN1_SEQUENCE |
                                           MBEDTLS_ASN1_CONSTRUCTED ),
                     0 );
-        TEST_EQUAL( p + len, end );
+        TEST_EQUAL( len, end - p );
         if( ! mbedtls_test_asn1_skip_integer( &p, end, bits, bits, 1 ) )
             goto exit;
         if( ! mbedtls_test_asn1_skip_integer( &p, end, 2, bits, 1 ) )
             goto exit;
-        TEST_EQUAL( p, end );
+        TEST_EQUAL( p - end, 0 );
 
 
         TEST_ASSERT( exported_length <=