diff --git a/src/http/ngx_http_request.c b/src/http/ngx_http_request.c
index 3f50666..0f30a31 100644
--- a/src/http/ngx_http_request.c
+++ b/src/http/ngx_http_request.c
@@ -943,7 +943,8 @@
          * in CPU cache
          */
 
-        ua = ngx_strstr(r->headers_in.user_agent->value.data, "MSIE");
+        ua = (u_char *) ngx_strstr(r->headers_in.user_agent->value.data,
+                                   "MSIE");
         if (ua
             && ua + 8 < r->headers_in.user_agent->value.data
                                          + r->headers_in.user_agent->value.len)