diff --git a/libmudflap/ChangeLog b/libmudflap/ChangeLog
index aa88a7326eb..1e74ddec48e 100644
--- a/libmudflap/ChangeLog
+++ b/libmudflap/ChangeLog
@@ -1,3 +1,8 @@
+2010-08-20  Uros Bizjak  <ubizjak@gmail.com>
+
+	* testsuite/libmudflap.c++/pass41-frag.cxx (dg-prune-output):
+	New dg directive.
+
 2010-06-09  Iain Sandoe  <iains@gcc.gnu.org>
 
 	PR bootstrap/43170
diff --git a/libmudflap/testsuite/libmudflap.c++/pass41-frag.cxx b/libmudflap/testsuite/libmudflap.c++/pass41-frag.cxx
index d15b98f1cdd..06896c7f6e7 100644
--- a/libmudflap/testsuite/libmudflap.c++/pass41-frag.cxx
+++ b/libmudflap/testsuite/libmudflap.c++/pass41-frag.cxx
@@ -8,3 +8,6 @@ main (int argc, char *argv[])
     std::cout << myStr << std::endl;
     return 0;
 }
+
+/* Ignore a warning that is irrelevant to the purpose of this test.  */
+/* { dg-prune-output ".*mudflap cannot track unknown size extern.*" } */