diff --git a/config/Rules.am b/config/Rules.am
index bb188427ea..b22b724a69 100644
--- a/config/Rules.am
+++ b/config/Rules.am
@@ -1,7 +1,7 @@
 DEFAULT_INCLUDES = -include ${top_srcdir}/zfs_config.h
 
 AM_LIBTOOLFLAGS = --silent
-AM_CFLAGS  = -Wall -Wstrict-prototypes -fno-strict-aliasing -Werror
+AM_CFLAGS  = -Wall -Wstrict-prototypes -fno-strict-aliasing ${DEBUG_CFLAGS}
 AM_CFLAGS += -D_GNU_SOURCE -D__EXTENSIONS__ -D_REENTRANT
 AM_CFLAGS += -D_POSIX_PTHREAD_SEMANTICS -D_FILE_OFFSET_BITS=64
 AM_CFLAGS += -D_LARGEFILE64_SOURCE -DTEXT_DOMAIN=\"zfs-linux-user\"
diff --git a/config/kernel.m4 b/config/kernel.m4
index 9c65b0feec..4cea344ccd 100644
--- a/config/kernel.m4
+++ b/config/kernel.m4
@@ -25,7 +25,7 @@ AC_DEFUN([ZFS_AC_CONFIG_KERNEL], [
 
 	dnl # -Wall -fno-strict-aliasing -Wstrict-prototypes and other
 	dnl # compiler options are added by the kernel build system.
-	KERNELCPPFLAGS="$KERNELCPPFLAGS -Werror -DHAVE_SPL -D_KERNEL"
+	KERNELCPPFLAGS="$KERNELCPPFLAGS -DHAVE_SPL -D_KERNEL"
 	KERNELCPPFLAGS="$KERNELCPPFLAGS -DTEXT_DOMAIN=\\\"zfs-linux-kernel\\\""
 	KERNELCPPFLAGS="$KERNELCPPFLAGS -I$SPL"
 	KERNELCPPFLAGS="$KERNELCPPFLAGS -I$SPL/include"
diff --git a/config/zfs-build.m4 b/config/zfs-build.m4
index 0bc31fd266..1401b72fd0 100644
--- a/config/zfs-build.m4
+++ b/config/zfs-build.m4
@@ -8,33 +8,26 @@ AC_DEFUN([ZFS_AC_LICENSE], [
 
 AC_DEFUN([ZFS_AC_DEBUG], [
 	AC_MSG_CHECKING([whether debugging is enabled])
-	AC_ARG_ENABLE( [debug],
-		AS_HELP_STRING([--enable-debug],
-		[Enable generic debug support (default off)]),
-		[ case "$enableval" in
-			yes) zfs_ac_debug=yes ;;
-			no)  zfs_ac_debug=no  ;;
-			*) AC_MSG_RESULT([Error!])
-			AC_MSG_ERROR([Bad value "$enableval" for --enable-debug]) ;;
-		esac ]
-)
-if test "$zfs_ac_debug" = yes; then
-	AC_MSG_RESULT([yes])
-		AC_DEFINE([DEBUG], [1],
-		[Define to 1 to enable debug tracing])
-		KERNELCPPFLAGS="${KERNELCPPFLAGS} -DDEBUG "
-		HOSTCFLAGS="${HOSTCFLAGS} -DDEBUG "
-		USERDEBUG="-DDEBUG -fstack-check"
-	else
-		AC_MSG_RESULT([no])
-		AC_DEFINE([NDEBUG], [1],
-		[Define to 1 to disable debug tracing])
+	AC_ARG_ENABLE([debug],
+		[AS_HELP_STRING([--enable-debug],
+		[Enable generic debug support @<:@default=no@:>@])],
+		[],
+		[enable_debug=no])
+
+	AS_IF([test "x$enable_debug" = xyes],
+	[
+		KERNELCPPFLAGS="${KERNELCPPFLAGS} -DDEBUG -Werror"
+		HOSTCFLAGS="${HOSTCFLAGS} -DDEBUG -Werror"
+		DEBUG_CFLAGS="-DDEBUG -Werror -fstack-check"
+	],
+	[
 		KERNELCPPFLAGS="${KERNELCPPFLAGS} -DNDEBUG "
 		HOSTCFLAGS="${HOSTCFLAGS} -DNDEBUG "
-		USERDEBUG="-DNDEBUG"
-	fi
+		DEBUG_CFLAGS="-DNDEBUG"
+	])
 
-	AC_SUBST(USERDEBUG)
+	AC_SUBST(DEBUG_CFLAGS)
+	AC_MSG_RESULT([$enable_debug])
 ])
 
 AC_DEFUN([ZFS_AC_CONFIG_SCRIPT], [