diff --git a/lib/nghttp2_helper.c b/lib/nghttp2_helper.c
index fac1dd29..d0fa867a 100644
--- a/lib/nghttp2_helper.c
+++ b/lib/nghttp2_helper.c
@@ -125,7 +125,7 @@ const char* nghttp2_strerror(int error_code)
   case NGHTTP2_ERR_DEFERRED_DATA_EXIST:
     return "Another DATA frame has already been deferred";
   case NGHTTP2_ERR_START_STREAM_NOT_ALLOWED:
-    return "SYN_STREAM is not allowed";
+    return "request HEADERS is not allowed";
   case NGHTTP2_ERR_GOAWAY_ALREADY_SENT:
     return "GOAWAY has already been sent";
   case NGHTTP2_ERR_INVALID_HEADER_BLOCK: