diff -Nru grafx2-2.6/debian/changelog grafx2-2.6/debian/changelog
--- grafx2-2.6/debian/changelog	2019-01-10 15:51:38.000000000 +0000
+++ grafx2-2.6/debian/changelog	2019-01-21 12:44:37.000000000 +0000
@@ -1,3 +1,9 @@
+grafx2 (2.6-2) unstable; urgency=medium
+
+  * Patch src/fileformats to fix png saving.
+
+ -- Gürkan Myczko <gurkan@phys.ethz.ch>  Mon, 21 Jan 2019 13:44:37 +0100
+
 grafx2 (2.6-1) unstable; urgency=medium
 
   * New upstream version. (Closes: #918725)
diff -Nru grafx2-2.6/debian/patches/fix-png-save-segfault grafx2-2.6/debian/patches/fix-png-save-segfault
--- grafx2-2.6/debian/patches/fix-png-save-segfault	1970-01-01 00:00:00.000000000 +0000
+++ grafx2-2.6/debian/patches/fix-png-save-segfault	2019-01-21 12:44:37.000000000 +0000
@@ -0,0 +1,80 @@
+Description: <short summary of the patch>
+ TODO: Put a short summary on the line above and replace this paragraph
+ with a longer explanation of this change. Complete the meta-information
+ with other relevant fields (see below for details). To make it easier, the
+ information below has been extracted from the changelog. Adjust it or drop
+ it.
+ .
+ grafx2 (2.6-2) unstable; urgency=medium
+ .
+   * Patch src/fileformats to fix png saving.
+Author: Gürkan Myczko <gurkan@phys.ethz.ch>
+
+---
+The information above should follow the Patch Tagging Guidelines, please
+checkout http://dep.debian.net/deps/dep3/ to learn about the format. Here
+are templates for supplementary fields that you might want to add:
+
+Origin: <vendor|upstream|other>, <url of original patch>
+Bug: <url in upstream bugtracker>
+Bug-Debian: https://bugs.debian.org/<bugnumber>
+Bug-Ubuntu: https://launchpad.net/bugs/<bugnumber>
+Forwarded: <no|not-needed|url proving that it has been forwarded>
+Reviewed-By: <name and email of someone who approved the patch>
+Last-Update: 2019-01-21
+
+--- grafx2-2.6.orig/src/fileformats.c
++++ grafx2-2.6/src/fileformats.c
+@@ -6798,6 +6798,7 @@ void Save_PNG_Sub(T_IO_Context * context
+   byte cycle_data[16*6]; // Storage for color-cycling data, referenced by crng_chunk
+   struct PNG_memory_buffer memory_buffer;
+ 
++  memset(&memory_buffer, 0, sizeof(memory_buffer));
+   /* initialisation */
+   if ((png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL))
+       && (info_ptr = png_create_info_struct(png_ptr)))
+@@ -6806,14 +6807,10 @@ void Save_PNG_Sub(T_IO_Context * context
+     {
+       if (file != NULL)
+         png_init_io(png_ptr, file);
+-      else
+-      {
+-        // to write to memory, use png_set_write_fn() instead of calling png_init_io()
+-        memset(&memory_buffer, 0, sizeof(memory_buffer));
++      else // to write to memory, use png_set_write_fn() instead of calling png_init_io()
+         png_set_write_fn(png_ptr, &memory_buffer, PNG_memory_write, PNG_memory_flush);
+-      }
+-      
+-      /* en-tete */
++
++      /* read PNG header */
+       if (!setjmp(png_jmpbuf(png_ptr)))
+       {
+         png_set_IHDR(png_ptr, info_ptr, context->Width, context->Height,
+@@ -6822,8 +6819,7 @@ void Save_PNG_Sub(T_IO_Context * context
+ 
+         png_set_PLTE(png_ptr, info_ptr, (png_colorp)context->Palette, 256);
+         {
+-          // Commentaires texte PNG
+-          // Cette partie est optionnelle
++          // text chunks in PNG (optional)
+           png_text text_ptr[2] = {
+ #ifdef PNG_iTXt_SUPPORTED
+             {-1, "Software", "Grafx2", 6, 0, NULL, NULL},
+@@ -6960,11 +6956,14 @@ void Save_PNG_Sub(T_IO_Context * context
+ 
+   if (Row_pointers)
+     free(Row_pointers);
+-  if (memory_buffer.buffer)
++  if (File_error == 0 && buffer != NULL)
+   {
+     *buffer = memory_buffer.buffer;
+-    *buffer_size = memory_buffer.offset;
++    if (buffer_size != NULL)
++      *buffer_size = memory_buffer.offset;
+   }
++  else
++    free(memory_buffer.buffer);
+ }
+ 
+ 
diff -Nru grafx2-2.6/debian/patches/series grafx2-2.6/debian/patches/series
--- grafx2-2.6/debian/patches/series	2018-12-10 08:06:17.000000000 +0000
+++ grafx2-2.6/debian/patches/series	2019-01-21 12:44:37.000000000 +0000
@@ -1 +1,2 @@
 sdl2-api
+fix-png-save-segfault