diff -Nru giflib-5.2.1/debian/changelog giflib-5.2.1/debian/changelog
--- giflib-5.2.1/debian/changelog	2022-04-27 18:17:29.000000000 +0000
+++ giflib-5.2.1/debian/changelog	2022-06-12 16:32:15.000000000 +0000
@@ -1,3 +1,11 @@
+giflib (5.2.1-2.5) unstable; urgency=medium
+
+  * Non-maintainer upload
+  * Move declaration of GifQuantizeBuffer() back to gif_lib.h
+    (Closes: #1011705)
+
+ -- Graham Inggs <ginggs@debian.org>  Sun, 12 Jun 2022 16:32:15 +0000
+
 giflib (5.2.1-2.4) unstable; urgency=medium
 
   * Non-maintainer upload.
diff -Nru giflib-5.2.1/debian/patches/giflib_quantize-header.patch giflib-5.2.1/debian/patches/giflib_quantize-header.patch
--- giflib-5.2.1/debian/patches/giflib_quantize-header.patch	1970-01-01 00:00:00.000000000 +0000
+++ giflib-5.2.1/debian/patches/giflib_quantize-header.patch	2022-06-12 16:32:10.000000000 +0000
@@ -0,0 +1,40 @@
+Description: Move declaration of GifQuantizeBuffer() back to gif_lib.h
+Bug-Debian: https://bugs.debian.org/1011705
+Author: Graham Inggs <ginggs@debian.org>
+Last-Update: 2022-06-12
+
+--- a/gif_lib.h
++++ b/gif_lib.h
+@@ -215,6 +215,14 @@
+ int DGifGetLZCodes(GifFileType *GifFile, int *GifCode);
+ const char *DGifGetGifVersion(GifFileType *GifFile);
+ 
++/******************************************************************************
++ Color table quantization (deprecated)
++******************************************************************************/
++int GifQuantizeBuffer(unsigned int Width, unsigned int Height,
++                   int *ColorMapSize, GifByteType * RedInput,
++                   GifByteType * GreenInput, GifByteType * BlueInput,
++                   GifByteType * OutputBuffer,
++                   GifColorType * OutputColorMap);
+ 
+ /******************************************************************************
+  Error handling and reporting.
+--- a/getarg.h
++++ b/getarg.h
+@@ -34,15 +34,6 @@
+ extern void GifQprintf(char *Format, ...);
+ extern void PrintGifError(int ErrorCode);
+ 
+-/******************************************************************************
+- Color table quantization
+-******************************************************************************/
+-int GifQuantizeBuffer(unsigned int Width, unsigned int Height,
+-                   int *ColorMapSize, GifByteType * RedInput,
+-                   GifByteType * GreenInput, GifByteType * BlueInput,
+-                   GifByteType * OutputBuffer,
+-                   GifColorType * OutputColorMap);
+-
+ /* These used to live in the library header */
+ #define GIF_MESSAGE(Msg) fprintf(stderr, "\n%s: %s\n", PROGRAM_NAME, Msg)
+ #define GIF_EXIT(Msg)    { GIF_MESSAGE(Msg); exit(-3); }
diff -Nru giflib-5.2.1/debian/patches/series giflib-5.2.1/debian/patches/series
--- giflib-5.2.1/debian/patches/series	2022-04-22 12:22:57.000000000 +0000
+++ giflib-5.2.1/debian/patches/series	2022-06-12 16:30:10.000000000 +0000
@@ -6,3 +6,4 @@
 30_link_utils_dynamically.diff
 giflib_quantize.patch
 dont-spoil-tests-with-stderr.patch
+giflib_quantize-header.patch