diff -pruN 0.8.3-4.3/debian/changelog 0.8.3-4.4/debian/changelog
--- 0.8.3-4.3/debian/changelog	2025-01-04 12:30:21.000000000 +0000
+++ 0.8.3-4.4/debian/changelog	2025-09-22 19:54:46.000000000 +0000
@@ -1,3 +1,10 @@
+dia2code (0.8.3-4.4) unstable; urgency=medium
+
+  * Non-maintainer upload.
+  * Fix FTBFS with GCC 15. (Closes: #1096521)
+
+ -- Adrian Bunk <bunk@debian.org>  Mon, 22 Sep 2025 22:54:46 +0300
+
 dia2code (0.8.3-4.3) unstable; urgency=medium
 
   * Non-maintainer upload.
diff -pruN 0.8.3-4.3/debian/patches/gcc-15.patch 0.8.3-4.4/debian/patches/gcc-15.patch
--- 0.8.3-4.3/debian/patches/gcc-15.patch	1970-01-01 00:00:00.000000000 +0000
+++ 0.8.3-4.4/debian/patches/gcc-15.patch	2025-09-22 19:54:46.000000000 +0000
@@ -0,0 +1,17 @@
+Description: Fix FTBFS with GCC 15
+Author: Adrian Bunk <bunk@debian.org>
+Bug-Debian: https://bugs.debian.org/1096521
+
+--- dia2code-0.8.3.orig/dia2code/dia2code.h
++++ dia2code-0.8.3/dia2code/dia2code.h
+@@ -232,8 +232,8 @@ FILE * open_outfile (char *filename, bat
+ #define d2c_fputc fputc
+ #endif
+ 
+-void d2c_indent();
+-void d2c_outdent();
++void d2c_indent(FILE *f);
++void d2c_outdent(FILE *f);
+ int _d2c_fputs(const char *s, FILE *f);
+ int _d2c_fputc(int c, FILE *f);
+ int _d2c_fprintf(FILE *f, char *fmt, ...);
diff -pruN 0.8.3-4.3/debian/patches/series 0.8.3-4.4/debian/patches/series
--- 0.8.3-4.3/debian/patches/series	2025-01-04 12:27:43.000000000 +0000
+++ 0.8.3-4.4/debian/patches/series	2025-09-22 19:54:46.000000000 +0000
@@ -6,3 +6,4 @@ pkg-config.patch
 generate_code_java.patch
 parse_diagram-header.patch
 fprint-arg-ruby.patch
+gcc-15.patch