diff --git a/pkgs/tools/misc/kermit/default.nix b/pkgs/tools/misc/kermit/default.nix
index ddb51adc6c9..2155b8676be 100644
--- a/pkgs/tools/misc/kermit/default.nix
+++ b/pkgs/tools/misc/kermit/default.nix
@@ -16,7 +16,7 @@ stdenv.mkDerivation {
     tar xvzf $src
   '';
 
-  patchPhase = ''
+  postPatch = ''
     sed -i -e 's@-I/usr/include/ncurses@@' \
       -e 's@/usr/local@'"$out"@ makefile
   '';