diff --git a/coders/html.c b/coders/html.c
index fe97a43333..1b9abb38d7 100644
--- a/coders/html.c
+++ b/coders/html.c
@@ -94,7 +94,7 @@ static MagickBooleanType
 */
 static MagickBooleanType IsHTML(const unsigned char *magick,const size_t length)
 {
-  if (length < 5)
+  if (length < 6)
     return(MagickFalse);
   if (LocaleNCompare((char *) magick+1,"html",5) == 0)
     return(MagickTrue);