--- plotutils-2.6.old/libplot/z_write.c
+++ plotutils-2.6/libplot/z_write.c
@@ -65,6 +65,26 @@
 #endif
 #endif
 
+/* starting from libpng version 1.5 it is not possible
+ * to access inside the PNG struct directly
+ */
+
+#ifdef PNG_SETJMP
+#undef PNG_SETJMP
+#endif
+
+#ifdef PNG_LONGJMP
+#undef PNG_LONGJMP
+#endif
+
+#if (defined(PNG_LIBPNG_VER) && PNG_LIBPNG_VER >= 10500)
+#define PNG_SETJMP(ptr) setjmp(png_jmpbuf(ptr))
+#define PNG_LONGJMP(ptr) longjmp(png_jmpbuf(ptr), 1)
+#else
+#define PNG_SETJMP(ptr) setjmp(ptr->jmpbuf)
+#define PNG_LONGJMP(ptr) longjmp(ptr->jmpbuf, 1)
+#endif
+
 static const char _short_months[12][4] = 
 { "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" };
 
@@ -164,7 +184,7 @@
     }
 
   /* cleanup after libpng errors (error handler does a longjmp) */
-  if (setjmp (png_ptr->jmpbuf))
+  if (PNG_SETJMP(png_ptr))
     {
       png_destroy_write_struct (&png_ptr, (png_info **)NULL);
       return -1;
@@ -444,7 +464,7 @@
 #endif
     }
 
-  longjmp (png_ptr->jmpbuf, 1);
+  PNG_LONGJMP(png_ptr);
 }
 
 static void 
@@ -515,7 +535,7 @@
 #endif
     }
 
-  longjmp (png_ptr->jmpbuf, 1);
+  longjmp (png_jmpbuf (png_ptr), 1);
 }
 
 static void