diff --git a/aclocal.m4 b/aclocal.m4
index 364526e2785cd3b565f81b16d936435cc6c37756..3ecbc1f507aa254aacde4d451797f186d14f86fb 100644
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -279,7 +279,7 @@ AC_DEFUN(AC_PROG_GNUCPP,
 [if test "$HaveGcc" = "YES"; then
 	echo > conftest.c
 	gcc -v -E conftest.c >/dev/null 2>conftest.out
-	echo 'tr /\\/\// ; /(\S+\/cpp)/ && print "[$]1";' > conftest.pl
+	echo 'tr/\\/\//; /(\S+\/cpp)/ && print "[$]1";' > conftest.pl
 	ac_cv_gnu_cpp="`eval $PerlCmd -n conftest.pl conftest.out`"
 	rm -fr conftest*
  else