diff --git a/src/util/string.h b/src/util/string.h
index b78e20180..837f7b55b 100644
--- a/src/util/string.h
+++ b/src/util/string.h
@@ -3,7 +3,11 @@
 
 #include "util/common.h"
 
+#ifndef strndup
+// This is sometimes a macro
 char* strndup(const char* start, size_t len);
+#endif
+
 char* strnrstr(const char* restrict s1, const char* restrict s2, size_t len);
 
 #endif