diff --git a/source/tutorials/packaging-existing-software.md b/source/tutorials/packaging-existing-software.md
index dd41dad..28e8cf1 100644
--- a/source/tutorials/packaging-existing-software.md
+++ b/source/tutorials/packaging-existing-software.md
@@ -460,7 +460,7 @@ stdenv.mkDerivation {
     owner = "atextor";
     repo = "icat";
     rev = "v0.5";
-	sha256 = "0wyy2ksxp95vnh71ybj1bbmqd5ggp13x3mk37pzr99ljs9awy8ka";
+    sha256 = "0wyy2ksxp95vnh71ybj1bbmqd5ggp13x3mk37pzr99ljs9awy8ka";
   };
 
   buildInputs = [ imlib2 xorg.libX11.dev ];