diff --git a/src/util/conf.c b/src/util/conf.c
index aaf5a54..73a7d5f 100644
--- a/src/util/conf.c
+++ b/src/util/conf.c
@@ -70,7 +70,7 @@ int conf_procbuf(char const* restrict buf, size_t buflen, struct conf_entry cons
 }
 
 /* utility function for conf_getpat to concatenate 3 strings, where we already know the size */
-static inline char* conf_getpat_concat(char const* restrict s1, char const* restrict s2, char const* restrict s3, size_t s1len, size_t s2len, size_t s3len) __attribute_nonnull__((1, 3)) {
+__nonnull((1, 3)) static inline char* conf_getpat_concat(char const* restrict s1, char const* restrict s2, char const* restrict s3, size_t s1len, size_t s2len, size_t s3len) {
 	char *buf, *ptr;
 
 	// allocate enough data for all three to the buffer