diff --git a/configure.ac b/configure.ac
index c73f66b6..b3cb13a9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -306,11 +306,10 @@ AS_CASE([$host_os],
   ])
 ])
 
-AC_ARG_VAR([CWFLAGS], [define to compilation flags for generating extra warnings])
-
 AX_CHECK_COMPILE_FLAG([$CFLAGS -Wall], [CWFLAGS="$CFLAGS -Wall"])
-AX_CHECK_COMPILE_FLAG([$CFLAGS -Wextra], [CWFLAGS="$CFLAGS -Wextra"])
-AX_CHECK_COMPILE_FLAG([$CFLAGS -Wno-deprecated-declarations], [CWFLAGS="$CFLAGS -Wno-deprecated-declarations"])
+AX_CHECK_COMPILE_FLAG([$CFLAGS -Wno-deprecated-declarations], [CFLAGS="$CFLAGS -Wno-deprecated-declarations"])
+
+AC_ARG_VAR([CWFLAGS], [compilation flags for generating extra warnings])
 
 AC_MSG_CHECKING(for clang)
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]], [[
@@ -325,6 +324,7 @@ AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]], [[
   [AC_MSG_RESULT(no)
 ])
 
+AX_CHECK_COMPILE_FLAG([$CWFLAGS -Wextra], [CWFLAGS="$WCFLAGS -Wextra"])
 AX_CHECK_COMPILE_FLAG([$CWFLAGS -Warray-bounds], [CWFLAGS="$CWFLAGS -Warray-bounds"])
 AX_CHECK_COMPILE_FLAG([$CWFLAGS -Wbad-function-cast], [CWFLAGS="$CWFLAGS -Wbad-function-cast"])
 AX_CHECK_COMPILE_FLAG([$CWFLAGS -Wcast-qual], [CWFLAGS="$CWFLAGS -Wcast-qual"])