diff --git a/tools/pkcs1-conv.c b/tools/pkcs1-conv.c
index 0722b6b9f5c7d0adbe1e2428a37706cf3e4fced2..d402da07cbd0fcdb2a2b213254351ab4eb36f2d4 100644
--- a/tools/pkcs1-conv.c
+++ b/tools/pkcs1-conv.c
@@ -186,9 +186,11 @@ read_pem(struct nettle_buffer *buffer, FILE *f,
   /* Find start line */
   for (;;)
     {
+      int res;
+
       nettle_buffer_reset(buffer);
 
-      int res = read_line(buffer, f);
+      res = read_line(buffer, f);
       if (res != 1)
 	return res;