diff --git a/configure.ac b/configure.ac
index 46975753..34774010 100644
--- a/configure.ac
+++ b/configure.ac
@@ -43,6 +43,7 @@ AC_C_BIGENDIAN
 AC_C_CONST
 AC_C_INLINE
 AC_C___ATTRIBUTE__
+AC_C___FUNC__
 AC_CHECK_SIZEOF(int, 4)
 AC_CHECK_SIZEOF(long, 4)
 AC_CHECK_SIZEOF(wchar_t, 4)
diff --git a/m4/ac_func.m4 b/m4/ac_func.m4
new file mode 100644
index 00000000..6c0b579c
--- /dev/null
+++ b/m4/ac_func.m4
@@ -0,0 +1,35 @@
+dnl Copyright (C) 2010 Kim Woelders
+dnl This code is public domain and can be freely used or copied.
+
+dnl Macro for defining __func__ if not already defined
+
+dnl Usage: AC_C___FUNC__
+
+dnl If __func__ is not defined and __FUNCTION__ is, __func__ is defined
+dnl to __FUNCTION__. If __FUNCTION__ isn't defined either, __func__ is
+dnl defined to "FUNC".
+
+AC_DEFUN([AC_C___FUNC__],
+[
+  AC_CACHE_CHECK([for __func__], ac_cv___func__, [
+    AC_COMPILE_IFELSE([
+      AC_LANG_PROGRAM([], [[const char *s = __func__;]])
+    ], [
+      ac_cv___func__=yes
+    ], [
+      AC_COMPILE_IFELSE([
+        AC_LANG_PROGRAM([], [[const char *s = __FUNCTION__;]])
+      ], [
+        ac_cv___func__=function
+      ], [
+        ac_cv___func__=no
+      ])
+    ])
+  ])
+
+  if test $ac_cv___func__ = function; then
+    AC_DEFINE(__func__, __FUNCTION__, [Define __func__ appropriately if missing])
+  elif test $ac_cv___func__ = no; then
+    AC_DEFINE(__func__, "FUNC", [Define __func__ appropriately if missing])
+  fi
+])