diff --git a/pkgs/applications/networking/instant-messengers/tkabber/default.nix b/pkgs/applications/networking/instant-messengers/tkabber/default.nix
index 69c404f33b4..53a334f6869 100644
--- a/pkgs/applications/networking/instant-messengers/tkabber/default.nix
+++ b/pkgs/applications/networking/instant-messengers/tkabber/default.nix
@@ -1,5 +1,7 @@
 { stdenv, fetchurl, tcl, tk, tcllib, tcltls, tclgpg
-, bwidget, makeWrapper, x11 }:
+, bwidget, makeWrapper, x11
+, theme ? null
+}:
 
 let
   tclLibraries = [ bwidget tcllib tcltls tclgpg ];
@@ -17,15 +19,14 @@ in stdenv.mkDerivation rec {
     sha256 = "49ee6e897dfe52ebac256531b54955e6b39223f606a9b8ad63a52475389db206";
   };
 
-  defaultTheme = "ocean-deep";
-
   patchPhase = ''
     substituteInPlace login.tcl --replace \
       "custom::defvar loginconf(sslcacertstore) \"\"" \
       "custom::defvar loginconf(sslcacertstore) \$env(OPENSSL_X509_CERT_FILE)"
-
+  '' + stdenv.lib.optionalString (theme != null) ''
+    themePath="$out/share/doc/tkabber/examples/xrdb/${theme}.xrdb"
     sed -i '/^if.*load_default_xrdb/,/^}$/ {
-        s@option readfile \(\[fullpath [^]]*\]\)@option readfile "'"$out/share/doc/tkabber/examples/xrdb/${defaultTheme}.xrdb"'"@
+      s@option readfile \(\[fullpath [^]]*\]\)@option readfile "'"$themePath"'"@
     }' tkabber.tcl
   '';