diff --git a/lib/http_digest.c b/lib/http_digest.c
index 132f3930c..049b232e0 100644
--- a/lib/http_digest.c
+++ b/lib/http_digest.c
@@ -56,7 +56,7 @@ CURLcode Curl_input_digest(struct Curl_easy *data,
     digest = &data->state.digest;
   }
 
-  if(!checkprefix("Digest", header))
+  if(!checkprefix("Digest", header) || !ISSPACE(header[6]))
     return CURLE_BAD_CONTENT_ENCODING;
 
   header += strlen("Digest");