diff --git a/src/htsbuf.c b/src/htsbuf.c
index 03f49a3a..045fa071 100644
--- a/src/htsbuf.c
+++ b/src/htsbuf.c
@@ -384,6 +384,7 @@ htsbuf_append_and_escape_url(htsbuf_queue_t *hq, const char *s)
 
   while(1) {
     const char *esc;
+    char buf[4];
     C = *c++;
     
     if((C >= '0' && C <= '9') ||
@@ -396,7 +397,6 @@ htsbuf_append_and_escape_url(htsbuf_queue_t *hq, const char *s)
       esc = NULL;
     } else {
       static const char hexchars[16] = "0123456789ABCDEF";
-      char buf[4];
       buf[0] = '%';
       buf[1] = hexchars[(C >> 4) & 0xf];
       buf[2] = hexchars[C & 0xf];;