Index: src/cairo-png.c
===================================================================
RCS file: /cvs/cairo/cairo/src/cairo-png.c,v
retrieving revision 1.6
diff -u -r1.6 cairo-png.c
--- src/cairo-png.c	7 Apr 2005 19:56:43 -0000	1.6
+++ src/cairo-png.c	19 Apr 2005 02:03:10 -0000
@@ -242,7 +242,7 @@
     png_byte **row_pointers;
 
     sig_bytes = fread (png_sig, 1, PNG_SIG_SIZE, file);
-    if (png_check_sig (png_sig, sig_bytes) == 0)
+    if (sig_bytes != PNG_SIG_SIZE || png_check_sig (png_sig, sig_bytes) == 0)
 	goto BAIL1; /* FIXME: ERROR_NOT_PNG */
 
     /* XXX: Perhaps we'll want some other error handlers? */