diff -ur pdflib-4.0.3.orig/pdflib/p_png.c pdflib-4.0.3/pdflib/p_png.c
--- pdflib-4.0.3.orig/pdflib/p_png.c	2002-01-26 19:32:18.000000000 +0100
+++ pdflib-4.0.3/pdflib/p_png.c	2010-03-01 10:44:56.537284868 +0100
@@ -408,7 +408,7 @@
 	return -1;	/* Couldn't open PNG file */
     }
 
-    if (fread(sig, 1, 8, image->fp) == 0 || !png_check_sig(sig, 8)) {
+    if (fread(sig, 1, 8, image->fp) == 0 || !png_sig_cmp(sig, 0, 8)) {
 	fclose(image->fp);
 	png_destroy_read_struct(&image->info.png.png_ptr,
 		&image->info.png.info_ptr, NULL);
diff -ur pdflib-4.0.3.orig/png/png.c pdflib-4.0.3/png/png.c
--- pdflib-4.0.3.orig/png/png.c	2001-03-21 17:12:07.000000000 +0100
+++ pdflib-4.0.3/png/png.c	2010-03-01 10:45:38.760604885 +0100
@@ -125,16 +125,6 @@
    return ((int)(png_memcmp(&sig[start], &png_signature[start], num_to_check)));
 }
 
-/* (Obsolete) function to check signature bytes.  It does not allow one
- * to check a partial signature.  This function might be removed in the
- * future - use png_sig_cmp().  Returns true (nonzero) if the file is a PNG.
- */
-int PNGAPI
-png_check_sig(png_bytep sig, int num)
-{
-  return ((int)!png_sig_cmp(sig, (png_size_t)0, (png_size_t)num));
-}
-
 /* Function to allocate memory for zlib and clear it to 0. */
 voidpf PNGAPI
 png_zalloc(voidpf png_ptr, uInt items, uInt size)
diff -ur pdflib-4.0.3.orig/png/pngconf.h pdflib-4.0.3/png/pngconf.h
--- pdflib-4.0.3.orig/png/pngconf.h	2002-03-25 17:06:09.000000000 +0100
+++ pdflib-4.0.3/png/pngconf.h	2010-03-01 10:45:07.647274500 +0100
@@ -35,7 +35,6 @@
 #define png_bKGD pdf_png_bKGD
 #define png_cHRM pdf_png_cHRM
 #define png_calculate_crc pdf_png_calculate_crc
-#define png_check_sig pdf_png_check_sig
 #define png_convert_to_rfc1123 pdf_png_convert_to_rfc1123
 #define png_create_info_struct pdf_png_create_info_struct
 #define png_data_freer pdf_png_data_freer
diff -ur pdflib-4.0.3.orig/png/png.h pdflib-4.0.3/png/png.h
--- pdflib-4.0.3.orig/png/png.h	2001-03-21 17:12:07.000000000 +0100
+++ pdflib-4.0.3/png/png.h	2010-03-01 10:45:25.460606752 +0100
@@ -1181,11 +1181,6 @@
 extern PNG_EXPORT(int,png_sig_cmp) PNGARG((png_bytep sig, png_size_t start,
    png_size_t num_to_check));
 
-/* Simple signature checking function.  This is the same as calling
- * png_check_sig(sig, n) := !png_sig_cmp(sig, 0, n).
- */
-extern PNG_EXPORT(int,png_check_sig) PNGARG((png_bytep sig, int num));
-
 /* Allocate and initialize png_ptr struct for reading, and any other memory. */
 extern PNG_EXPORT(png_structp,png_create_read_struct)
    PNGARG((png_const_charp user_png_ver, png_voidp error_ptr,