diff --git a/gitk b/gitk
index d9812f2e9c..342b0aba8d 100755
--- a/gitk
+++ b/gitk
@@ -33,6 +33,19 @@ The version of git found is $git_version."
     exit 1
 }
 
+######################################################################
+## Enable Tcl8 profile in Tcl9, allowing consumption of data that has
+## bytes not conforming to the assumed encoding profile.
+
+if {[package vcompare $::tcl_version 9.0] >= 0} {
+    rename open _strict_open
+    proc open args {
+        set f [_strict_open {*}$args]
+        chan configure $f -profile tcl8
+        return $f
+    }
+}
+
 ######################################################################
 ##
 ## Enabling platform-specific code paths