diff --git a/ChangeLog b/ChangeLog
index c9cf8b4b4..c7c3aa21b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2011-02-09  Alexandre Duret-Lutz  <adl@lrde.epita.fr>
+
+	Previous patch did not work on MacOS X, and I don't have shell
+	access to that host.
+
+	* src/tgbatest/kv.test: Use ${DOT-true} instead of ${DOT-:}.  I
+	don't know, the MacOS shell must be mixing the syntaxes for
+	${DOT:-} and ${DOT-:}.
+	* iface/nips/nipstest/dotty.test: Likewise
+
 2011-02-09  Alexandre Duret-Lutz  <adl@lrde.epita.fr>
 
 	Avoid running "dot" when it is not installed...
diff --git a/iface/nips/nipstest/dotty.test b/iface/nips/nipstest/dotty.test
index 7573dfbb1..62ac35244 100755
--- a/iface/nips/nipstest/dotty.test
+++ b/iface/nips/nipstest/dotty.test
@@ -26,6 +26,6 @@ set -e
 BYTECODE="never.pr.b regbit.b"
 for bytecode in $BYTECODE; do
     run 0 "$top_builddir/dottynips" "$srcdir/$bytecode" > dotty || exit 1
-    "${DOT-:}" -Tps dotty > /dev/null || exit 1
+    "${DOT-true}" -Tps dotty > /dev/null || exit 1
     rm -f dotty
 done
diff --git a/src/tgbatest/kv.test b/src/tgbatest/kv.test
index b3495b46d..2d16484b5 100755
--- a/src/tgbatest/kv.test
+++ b/src/tgbatest/kv.test
@@ -27,7 +27,7 @@ set -e
 check ()
 {
   run 0 ../ltl2tgba -f -KV "$1" > out.dot
-  "${DOT-:}" out.dot > /dev/null
+  "${DOT-true}" out.dot > /dev/null
   rm -f out.dot
 }