diff --git a/pkgs/by-name/mi/midicsv/fix-gcc15.patch b/pkgs/by-name/mi/midicsv/fix-gcc15.patch
new file mode 100644
index 000000000000..70ac4a0e5f19
--- /dev/null
+++ b/pkgs/by-name/mi/midicsv/fix-gcc15.patch
@@ -0,0 +1,12 @@
+diff --git a/getopt.c b/getopt.c
+index 1564e53..8db0459 100644
+--- a/getopt.c
++++ b/getopt.c
+@@ -73,7 +73,6 @@ int Getopt(int nargc, char *nargv[], char *ostr)
+         static char     *place = EMSG;  /* option letter processing */
+         static char     *lastostr = (char *) 0;
+         register char   *oli;           /* option letter list index */
+-        char    *index();
+ 
+         /* LANCE PATCH: dynamic reinitialization */
+         if (ostr != lastostr) {
diff --git a/pkgs/by-name/mi/midicsv/package.nix b/pkgs/by-name/mi/midicsv/package.nix
index 5edc2554770e..7476a77ac0cd 100644
--- a/pkgs/by-name/mi/midicsv/package.nix
+++ b/pkgs/by-name/mi/midicsv/package.nix
@@ -13,6 +13,10 @@ stdenv.mkDerivation (finalAttrs: {
     sha256 = "1vvhk2nf9ilfw0wchmxy8l13hbw9cnpz079nsx5srsy4nnd78nkw";
   };
 
+  patches = [
+    ./fix-gcc15.patch
+  ];
+
   postPatch = ''
     substituteInPlace Makefile \
       --replace /usr/local $out \