diff --git a/cddl/usr.sbin/dtrace/tests/tools/dtest.sh b/cddl/usr.sbin/dtrace/tests/tools/dtest.sh
index b5ad87440291..dc1f0244739c 100755
--- a/cddl/usr.sbin/dtrace/tests/tools/dtest.sh
+++ b/cddl/usr.sbin/dtrace/tests/tools/dtest.sh
@@ -1,3 +1,5 @@
+#!/bin/sh
+
 # $FreeBSD$
 
 usage()
@@ -84,6 +86,12 @@ runtest()
         ;;
     esac
 
+    if [ $retval -eq 0 ] && \
+        head -n 1 $STDOUT | grep -q -E '^#!/.*ksh$'; then
+        ksh $STDOUT
+        retval=$?
+    fi
+
     return $retval
 }