diff --git a/src/core/string.c b/src/core/string.c
index c35015b59..188fe0864 100644
--- a/src/core/string.c
+++ b/src/core/string.c
@@ -116,7 +116,7 @@ int memcmp ( const void *first, const void *second, size_t len ) {
 	int diff;
 
 	while ( len-- ) {
-		diff = ( *(second_bytes++) - *(first_bytes++) );
+		diff = ( *(first_bytes++) - *(second_bytes++) );
 		if ( diff )
 			return diff;
 	}
diff --git a/src/tests/string_test.c b/src/tests/string_test.c
index a66501da3..88a730aec 100644
--- a/src/tests/string_test.c
+++ b/src/tests/string_test.c
@@ -109,6 +109,7 @@ static void string_test_exec ( void ) {
 	ok ( memcmp ( "", "", 0 ) == 0 );
 	ok ( memcmp ( "Foo", "Foo", 3 ) == 0 );
 	ok ( memcmp ( "Foo", "Bar", 3 ) != 0 );
+	ok ( memcmp ( "abc", "def", 3 ) < 0 );
 
 	/* Test strstr() */
 	{