diff --git a/pkgs/by-name/sd/sdcc/package.nix b/pkgs/by-name/sd/sdcc/package.nix
index cc9e0512dcb4..82df34e70a2d 100644
--- a/pkgs/by-name/sd/sdcc/package.nix
+++ b/pkgs/by-name/sd/sdcc/package.nix
@@ -63,6 +63,16 @@ stdenv.mkDerivation (finalAttrs: {
       gputils
     ];
 
+  # sdcc 4.5.0 massively rewrote sim/ucsim/Makefile.in, and lost the `.PHONY`
+  # rule in the process. As a result, on macOS (which uses a case-insensitive
+  # filesystem), the INSTALL file keeps the `install` target in the ucsim
+  # directory from running. Nothing else creates the `man` output, causing the
+  # entire build to fail.
+
+  postPatch = ''
+    echo '.PHONY: install' >> sim/ucsim/Makefile.in
+  '';
+
   configureFlags =
     let
       excludedPorts =