diff --git a/src/string/strcmp.c b/src/string/strcmp.c
index f3ec3cc..5ec8600 100644
--- a/src/string/strcmp.c
+++ b/src/string/strcmp.c
@@ -6,5 +6,5 @@ int strcmp(const char *s1, const char *s2)
 		s1 += 1;
 		s2 += 1;
 	}
-	return (*s1 - *s2);
+	return ((unsigned char) *s1 - (unsigned char) *s2);
 }