diff --git a/src/shared-macro.h b/src/shared-macro.h
index 9f9dba28..4ef015f8 100644
--- a/src/shared-macro.h
+++ b/src/shared-macro.h
@@ -235,13 +235,13 @@ static inline bool streq_ptr(const char *a, const char *b)
  * This returns a pointer to the first character in @s that follows @prefix. If
  * @s does not start with @prefix, NULL is returned.
  */
-static inline char *startswith(const char *s, const char *prefix)
+static inline const char *startswith(const char *s, const char *prefix)
 {
 	size_t l;
 
 	l = strlen(prefix);
 	if (strncmp(s, prefix, l) == 0)
-		return (char*) s + l;
+		return s + l;
 
 	return NULL;
 }