diff --git a/pkgs/tools/inputmethods/ibus/default.nix b/pkgs/tools/inputmethods/ibus/default.nix
index cff24a631bbe..86b2931aebb3 100644
--- a/pkgs/tools/inputmethods/ibus/default.nix
+++ b/pkgs/tools/inputmethods/ibus/default.nix
@@ -50,13 +50,13 @@ in
 
 stdenv.mkDerivation rec {
   pname = "ibus";
-  version = "1.5.20";
+  version = "1.5.21";
 
   src = fetchFromGitHub {
     owner = "ibus";
     repo = "ibus";
     rev = version;
-    sha256 = "1npavb896qrp6qbqayb0va4mpsi68wybcnlbjknzgssqyw2ylh9r";
+    sha256 = "0fjbqj7d2g5c8i1wdggzhz269xisxv4xb1pa9swalm5p2b2vrjlx";
   };
 
   patches = [
diff --git a/pkgs/tools/inputmethods/ibus/fix-paths.patch b/pkgs/tools/inputmethods/ibus/fix-paths.patch
index 192aa7d6395e..60269c6c2418 100644
--- a/pkgs/tools/inputmethods/ibus/fix-paths.patch
+++ b/pkgs/tools/inputmethods/ibus/fix-paths.patch
@@ -40,6 +40,6 @@
  export IBUS_DATAROOTDIR=@datarootdir@
  export IBUS_LOCALEDIR=@localedir@
  export IBUS_LIBEXECDIR=${libexecdir}
--exec @PYTHON@ @prefix@/share/ibus/setup/main.py $@
+-exec ${PYTHON:-@PYTHON@} @prefix@/share/ibus/setup/main.py $@
 +exec @pythonInterpreter@ @prefix@/share/ibus/setup/main.py $@