diff --git a/lib/urlapi-int.h b/lib/urlapi-int.h
index 75a3605423..5f059c203a 100644
--- a/lib/urlapi-int.h
+++ b/lib/urlapi-int.h
@@ -7,7 +7,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2018, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2019, Daniel Stenberg, <daniel@haxx.se>, et al.
  *
  * This software is licensed as described in the file COPYING, which
  * you should have received as part of this distribution. The terms
@@ -22,9 +22,8 @@
  *
  ***************************************************************************/
 #include "curl_setup.h"
-/* scheme is not URL encoded, the longest libcurl supported ones are 6
-   letters */
-#define MAX_SCHEME_LEN 8
+/* scheme is not URL encoded, the longest libcurl supported ones are... */
+#define MAX_SCHEME_LEN 40
 
 bool Curl_is_absolute_url(const char *url, char *scheme, size_t buflen);
 char *Curl_concat_url(const char *base, const char *relurl);
diff --git a/lib/urlapi.c b/lib/urlapi.c
index 3fef2fcf77..d07e4f5dff 100644
--- a/lib/urlapi.c
+++ b/lib/urlapi.c
@@ -652,7 +652,7 @@ static CURLUcode seturl(const char *url, CURLU *u, unsigned int flags)
   char *fragment = NULL;
   CURLUcode result;
   bool url_has_scheme = FALSE;
-  char schemebuf[MAX_SCHEME_LEN];
+  char schemebuf[MAX_SCHEME_LEN + 1];
   char *schemep = NULL;
   size_t schemelen = 0;
   size_t urllen;
@@ -1217,6 +1217,9 @@ CURLUcode curl_url_set(CURLU *u, CURLUPart what,
 
   switch(what) {
   case CURLUPART_SCHEME:
+    if(strlen(part) > MAX_SCHEME_LEN)
+      /* too long */
+      return CURLUE_MALFORMED_INPUT;
     if(!(flags & CURLU_NON_SUPPORT_SCHEME) &&
        /* verify that it is a fine scheme */
        !Curl_builtin_scheme(part))
@@ -1279,7 +1282,7 @@ CURLUcode curl_url_set(CURLU *u, CURLUPart what,
     char *redired_url;
     CURLU *handle2;
 
-    if(Curl_is_absolute_url(part, NULL, MAX_SCHEME_LEN)) {
+    if(Curl_is_absolute_url(part, NULL, MAX_SCHEME_LEN + 1)) {
       handle2 = curl_url();
       if(!handle2)
         return CURLUE_OUT_OF_MEMORY;