diff --git a/ChangeLog b/ChangeLog
index 2129a89..19b764c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2007-02-15  Richard B. Kreckel  <kreckel@ginac.de>
+
+	* m4/cc.m4 (CL_HAVE_ATTRIBUTE_FLATTEN): More robust definition allows...
+	* src/base/cl_maybe_inline.h (CL_FLATTEN): ...simplification here.
+
 2007-02-10  Richard B. Kreckel  <kreckel@ginac.de>
 
 	* autoconf/ltmain.sh: Update to libtool-1.5.26.
diff --git a/m4/cc.m4 b/m4/cc.m4
index 0925662..768dba1 100644
--- a/m4/cc.m4
+++ b/m4/cc.m4
@@ -76,11 +76,15 @@ AC_CACHE_CHECK([whether the compiler supports __attribute__((flatten))], cl_cv_h
   cat > conftest.cc <<EOF
 void f() __attribute__((flatten));
 EOF
-AC_TRY_COMMAND(${CXX-g++} $CXXFLAGS -c conftest.cc >/dev/null 2>conftest.out)
-if grep -i "warning" conftest.out > /dev/null; then
-  cl_cv_have_attr_flatten=no
+if AC_TRY_COMMAND(${CXX-g++} $CXXFLAGS -c conftest.cc >/dev/null 2>conftest.stderr)
+then
+  if grep -i "warning" conftest.stderr > /dev/null; then
+    cl_cv_have_attr_flatten=no
+  else
+    cl_cv_have_attr_flatten=yes
+  fi
 else
-  cl_cv_have_attr_flatten=yes
+  cl_cv_have_attr_flatten=no
 fi
 rm -f conftest*
 ])
diff --git a/src/base/cl_maybe_inline.h b/src/base/cl_maybe_inline.h
index 9d185f4..77073a3 100644
--- a/src/base/cl_maybe_inline.h
+++ b/src/base/cl_maybe_inline.h
@@ -102,7 +102,7 @@
  *    a function.
  * 2. It's ignored if the optimization is switched off.
  */
-#if defined(__GNUC__) && defined(CL_HAVE_ATTRIBUTE_FLATTEN)
+#if defined(CL_HAVE_ATTRIBUTE_FLATTEN)
 #define CL_FLATTEN __attribute__((flatten))
 #else
 #define CL_FLATTEN