diff --git a/pkgs/applications/misc/khal/default.nix b/pkgs/applications/misc/khal/default.nix
index ae9576e6cbc..323fc501c84 100644
--- a/pkgs/applications/misc/khal/default.nix
+++ b/pkgs/applications/misc/khal/default.nix
@@ -41,6 +41,13 @@ with python3.pkgs; buildPythonApplication rec {
   checkInputs = [ pytest glibcLocales ];
   LC_ALL = "en_US.UTF-8";
 
+  postPatch = ''
+    sed -i \
+      -e "s/Invalid value for \"ics\"/Invalid value for \\\'ics\\\'/" \
+      -e "s/Invalid value for \"\[ICS\]\"/Invalid value for \\\'\[ICS\]\\\'/" \
+      tests/cli_test.py
+  '';
+
   postInstall = ''
     # zsh completion
     install -D misc/__khal $out/share/zsh/site-functions/__khal