diff --git a/lib/url.c b/lib/url.c
index eaa282a04c..2fd0a12837 100644
--- a/lib/url.c
+++ b/lib/url.c
@@ -5511,6 +5511,7 @@ static CURLcode create_conn(struct SessionHandle *data,
        we're gonna follow a Location: later or... then we need the protocol
        part added so that we have a valid URL. */
     char *reurl;
+    char *ch_lower;
 
     reurl = aprintf("%s://%s", conn->handler->scheme, data->change.url);
 
@@ -5519,6 +5520,10 @@ static CURLcode create_conn(struct SessionHandle *data,
       goto out;
     }
 
+    /* Change protocol prefix to lower-case */
+    for(ch_lower = reurl; *ch_lower != ':'; ch_lower++)
+      *ch_lower = (char)TOLOWER(*ch_lower);
+
     if(data->change.url_alloc) {
       Curl_safefree(data->change.url);
       data->change.url_alloc = FALSE;
diff --git a/tests/data/test1213 b/tests/data/test1213
index 729a7034da..4f22f0d92d 100644
--- a/tests/data/test1213
+++ b/tests/data/test1213
@@ -43,7 +43,7 @@ HTTP with proxy and host-only URL
 ^User-Agent:.*
 </strip>
 <protocol>
-GET HTTP://we.want.that.site.com.1213/ HTTP/1.1
+GET http://we.want.that.site.com.1213/ HTTP/1.1
 Host: we.want.that.site.com.1213
 Accept: */*
 Proxy-Connection: Keep-Alive