--- a/netwerk/protocol/http/nsHttpDigestAuth.cpp
+++ b/netwerk/protocol/http/nsHttpDigestAuth.cpp
@@ -561,18 +561,18 @@ nsHttpDigestAuth::ParseChallenge(const c
                                  uint16_t * algorithm,
                                  uint16_t * qop)
 {
   // put an absurd, but maximum, length cap on the challenge so
   // that calculations are 32 bit safe
   if (strlen(challenge) > 16000000) {
     return NS_ERROR_INVALID_ARG;
   }
-  
-  const char *p = challenge + 7; // first 7 characters are "Digest "
+
+  const char *p = challenge + 6; // first 6 characters are "Digest"
 
   *stale = false;
   *algorithm = ALGO_MD5; // default is MD5
   *qop = 0;
 
   for (;;) {
     while (*p && (*p == ',' || nsCRT::IsAsciiSpace(*p)))
       ++p;