diff --git a/pkgs/by-name/ic/icbm3d/package.nix b/pkgs/by-name/ic/icbm3d/package.nix
index 22a2fc0cc044..270e57c3045d 100644
--- a/pkgs/by-name/ic/icbm3d/package.nix
+++ b/pkgs/by-name/ic/icbm3d/package.nix
@@ -16,11 +16,22 @@ stdenv.mkDerivation (finalAttrs: {
 
   buildInputs = [ libX11 ];
 
+  buildFlags = [ "CC=${stdenv.cc.targetPrefix}cc" ]; # fix darwin and cross-compiled builds
+
   # Function are declared after they are used in the file, this is error since gcc-14.
   #   randnum.c:25:3: warning: implicit declaration of function 'srand' [-Wimplicit-function-declaration]
   #   randnum.c:33:7: warning: implicit declaration of function 'rand'; did you mean 'randnum'? [-Wimplicit-function-declaration]
   #   text.c:34:50: warning: implicit declaration of function 'strlen' [-Wimplicit-function-declaration]
-  env.NIX_CFLAGS_COMPILE = "-Wno-error=implicit-function-declaration";
+  postPatch = ''
+    substituteInPlace randnum.c --replace-fail 'stdio.h' 'stdlib.h'
+    sed -i '1i\
+    #include <string.h>' text.c
+
+    # The Makefile tries to install icbm3d immediately after building it, and
+    # ends up trying to copy it to /icbm3d. Normally this just gets an error
+    # and moves on, but it's probably better to not try it in the first place.
+    sed -i '/INSTALLROOT/d' makefile
+  '';
 
   installPhase = ''
     runHook preInstall
@@ -35,6 +46,6 @@ stdenv.mkDerivation (finalAttrs: {
     description = "3D vector-based clone of the atari game Missile Command";
     mainProgram = "icbm3d";
     license = lib.licenses.gpl2Plus;
-    platforms = lib.platforms.linux;
+    platforms = lib.platforms.unix;
   };
 })
diff --git a/pkgs/by-name/xg/xgalagapp/package.nix b/pkgs/by-name/xg/xgalagapp/package.nix
index 8afd7f29f069..0611ba0ae8fc 100644
--- a/pkgs/by-name/xg/xgalagapp/package.nix
+++ b/pkgs/by-name/xg/xgalagapp/package.nix
@@ -19,14 +19,20 @@ stdenv.mkDerivation rec {
     libXpm
   ];
 
-  buildPhase = ''
-    make all HIGH_SCORES_FILE=.xgalaga++.scores
-  '';
+  buildFlags = [
+    "all"
+    "HIGH_SCORES_FILE=.xgalaga++.scores"
+    "CXX=${stdenv.cc.targetPrefix}c++" # fix darwin and cross-compiled builds
+  ];
 
   installPhase = ''
+    runHook preInstall
+
     mkdir -p $out/bin $out/share/man
     mv xgalaga++ $out/bin
     mv xgalaga++.6x $out/share/man
+
+    runHook postInstall
   '';
 
   meta = with lib; {
@@ -34,6 +40,6 @@ stdenv.mkDerivation rec {
     description = "XGalaga++ is a classic single screen vertical shoot ’em up. It is inspired by XGalaga and reuses most of its sprites";
     mainProgram = "xgalaga++";
     license = licenses.gpl2Plus;
-    platforms = platforms.linux;
+    platforms = platforms.unix;
   };
 }