diff --git a/src/cf/linux-test3.m4 b/src/cf/linux-test3.m4
index 22d5b68a74..d72f8e79ca 100644
--- a/src/cf/linux-test3.m4
+++ b/src/cf/linux-test3.m4
@@ -109,4 +109,5 @@ AC_TRY_COMPILE(
   ac_cv_linux_kernel_sock_create_v=yes,
   ac_cv_linux_kernel_sock_create_v=no)])
 AC_MSG_RESULT($ac_cv_linux_kernel_sock_create_v)
+CPPFLAGS="$save_CPPFLAGS"])