diff --git a/ChangeLog b/ChangeLog
index 43f556c875..1f8e583ea1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,10 @@
 2012-05-01  Joseph Myers  <joseph@codesourcery.com>
 
+	* conform/conformtest.pl: Use -ansi for XPG3, XPG4 and UNIX98.
+	Use -std=c99 for XOPEN2K.
+	(@knownproblems): Remove.
+	(newtoken): Don't check %isknown.
+
 	* conform/data/math.h-data [XPG3 || XPG4 || UNIX98] (fpclassify):
 	Do not expect macro.
 	[XPG3 || XPG4 || UNIX98] (isfinite): Likewise.
diff --git a/conform/conformtest.pl b/conform/conformtest.pl
index 25e05a2998..f7933475d5 100644
--- a/conform/conformtest.pl
+++ b/conform/conformtest.pl
@@ -36,10 +36,10 @@ $CFLAGS{"ISO"} = "-ansi";
 $CFLAGS{"ISO99"} = "-std=c99";
 $CFLAGS{"ISO11"} = "-std=c1x -D_ISOC11_SOURCE";
 $CFLAGS{"POSIX"} = "-D_POSIX_C_SOURCE=199912 -ansi";
-$CFLAGS{"XPG3"} = "-D_XOPEN_SOURCE";
-$CFLAGS{"XPG4"} = "-D_XOPEN_SOURCE -D_XOPEN_SOURCE_EXTENDED";
-$CFLAGS{"UNIX98"} = "-D_XOPEN_SOURCE=500";
-$CFLAGS{"XOPEN2K"} = "-D_XOPEN_SOURCE=600";
+$CFLAGS{"XPG3"} = "-ansi -D_XOPEN_SOURCE";
+$CFLAGS{"XPG4"} = "-ansi -D_XOPEN_SOURCE -D_XOPEN_SOURCE_EXTENDED";
+$CFLAGS{"UNIX98"} = "-ansi -D_XOPEN_SOURCE=500";
+$CFLAGS{"XOPEN2K"} = "-std=c99 -D_XOPEN_SOURCE=600";
 $CFLAGS{"XOPEN2K8"} = "-std=c99 -D_XOPEN_SOURCE=700";
 $CFLAGS{"POSIX2008"} = "-std=c99 -D_POSIX_C_SOURCE=200809L";
 
@@ -76,14 +76,6 @@ while ($#keywords >= 0) {
   $iskeyword{pop (@keywords)} = 1;
 }
 
-# These are symbols which are known to pollute the namespace.
-@knownproblems = ('unix', 'linux', 'i386');
-
-# Make a hash table from the known problems.
-while ($#knownproblems >= 0) {
-  $isknown{pop (@knownproblems)} = 1;
-}
-
 $verbose = 1;
 
 $total = 0;
@@ -240,10 +232,6 @@ sub newtoken {
   for ($idx = 0; $idx <= $#allow; ++$idx) {
     return if (poorfnmatch ($allow[$idx], $token));
   }
-
-  unless ($isknown{$token}) {
-    $errors{$token} = 1;
-  }
 }