diff --git a/src/basic/strv.h b/src/basic/strv.h
index 87a7038a54..f82c76589d 100644
--- a/src/basic/strv.h
+++ b/src/basic/strv.h
@@ -45,7 +45,7 @@ static inline int strv_extend(char ***l, const char *value) {
         return strv_extend_with_size(l, NULL, value);
 }
 
-int strv_extendf(char ***l, const char *format, ...) _printf_(2,0);
+int strv_extendf(char ***l, const char *format, ...) _printf_(2,3);
 int strv_extend_front(char ***l, const char *value);
 
 int strv_push_with_size(char ***l, size_t *n, char *value);