diff --git a/config/kernel-bdi.m4 b/config/kernel-bdi.m4
index aec7b7347888..00bd37539cbe 100644
--- a/config/kernel-bdi.m4
+++ b/config/kernel-bdi.m4
@@ -8,9 +8,9 @@ AC_DEFUN([ZFS_AC_KERNEL_BDI], [
 		#include <linux/fs.h>
 
 		static const struct super_block
-		    sb __attribute__ ((unused)) {
+		    sb __attribute__ ((unused)) = {
 			.s_bdi = NULL,
-		}
+		};
 	],[
 	],[
 		AC_MSG_RESULT(yes)