--- a/GIFReader.st	Fri Oct 18 16:28:56 2019 +0200
+++ b/GIFReader.st	Fri Oct 18 16:29:02 2019 +0200
@@ -215,7 +215,14 @@
     inStream isNil ifTrue:[^ false].
     someBytes := inStream nextBytes:6.
     inStream close.
-    ^ self hasValidImageHeader:someBytes
+    ^ (someBytes size == 6) and:[self hasValidImageHeader:someBytes]
+
+    "
+     GIFReader isValidImageFile:'../../goodies/bitmaps/gifImages/a.gif'
+     GIFReader isValidImageFile:'../../goodies/bitmaps/gifImages/garfield.gif' 
+     GIFReader isValidImageFile:'fooBar'    
+     GIFReader isValidImageFile:'../../goodies/bitmaps/xpmBitmaps/device_images/ljet.xpm'      
+    "
 
     "Modified: 10.1.1997 / 15:40:34 / cg"
 ! !