diff --git a/gitk b/gitk
index c666435204..41e5071c4b 100755
--- a/gitk
+++ b/gitk
@@ -3503,7 +3503,8 @@ proc gitknewtmpdir {} {
 	} else {
 	    set tmpdir $gitdir
 	}
-	set gitktmpdir [file join $tmpdir [format ".gitk-tmp.%s" [pid]]]
+	set gitktmpformat [file join $tmpdir ".gitk-tmp.XXXXXX"]
+	set gitktmpdir [exec mktemp -d $gitktmpformat]
 	if {[catch {file mkdir $gitktmpdir} err]} {
 	    error_popup "[mc "Error creating temporary directory %s:" $gitktmpdir] $err"
 	    unset gitktmpdir