diff --git a/src/jplist.c b/src/jplist.c
index 218d75a..fbc963e 100644
--- a/src/jplist.c
+++ b/src/jplist.c
@@ -66,7 +66,7 @@
 }
 
 #ifndef HAVE_STRNDUP
-static char* strndup(char* str, size_t len)
+static char* strndup(const char* str, size_t len)
 {
     char *newstr = (char *)malloc(len+1);
     if (newstr) {