diff --git a/config/user-arch.m4 b/config/user-arch.m4
index 1ffa28b0eb..fcc566fc5d 100644
--- a/config/user-arch.m4
+++ b/config/user-arch.m4
@@ -2,20 +2,18 @@ dnl #
 dnl # Set the target arch for libspl atomic implementation
 dnl #
 AC_DEFUN([ZFS_AC_CONFIG_USER_ARCH], [
-	AC_MSG_CHECKING(for target arch)
+	AC_MSG_CHECKING(for target asm dir)
 	TARGET_ARCH=`echo ${target_cpu} | sed -e s/i.86/i386/`
-	TARGET_ARCH_DIR=asm-$TARGET_ARCH
-        AC_MSG_RESULT([$TARGET_ARCH])
 
 	case $TARGET_ARCH in
-	i386|x86_64|powerpc64)
-		AC_SUBST([TARGET_ARCH])
-		AC_SUBST([TARGET_ARCH_DIR])
+	i386|x86_64)
+		TARGET_ASM_DIR=asm-${TARGET_ARCH}
 		;;
 	*)
-                AC_MSG_ERROR([
-		*** Unsupported architecture $TARGET_ARCH
-		*** Available architectures: x86, x86_64, powerpc64])
+		TARGET_ASM_DIR=asm-generic
 		;;
 	esac
+
+	AC_SUBST([TARGET_ASM_DIR])
+	AC_MSG_RESULT([$TARGET_ASM_DIR])
 ])