diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index f3f7cb01d69d..5edf6fa44762 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1,8 +1,9 @@
 # SPDX-License-Identifier: GPL-2.0
 # Select 32 or 64 bit
 config 64BIT
-	bool "64-bit kernel" if "$(ARCH)" = "x86"
-	default "$(ARCH)" != "i386"
+	bool "64-bit kernel"
+	default ("$(ARCH)" != "i386") && \
+	    (("$(ARCH)" != "x86") || ("$(UARCH)" != "i386"))
 	help
 	  Say yes to build a 64-bit kernel - formerly known as x86_64
 	  Say no to build a 32-bit kernel - formerly known as i386
diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 46fec0b08487..166a1b6d3038 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -1,9 +1,15 @@
 # SPDX-License-Identifier: GPL-2.0
 # Unified Makefile for i386 and x86_64
 
+# For cases where build machine's architecture is relevant,
+#  "uname machine architecture" -> UARCH
+# Note we flatten i386/i486/i686 into a generic "i386" value
+UARCH := $(shell uname -m | sed -e 's/i.86/i386/')
+export UARCH
+
 # select defconfig based on actual architecture
 ifeq ($(ARCH),x86)
-  ifeq ($(shell uname -m | sed -e 's/i.86/i386/'),i386)
+  ifeq ($(UARCH),i386)
         KBUILD_DEFCONFIG := i386_defconfig
   else
         KBUILD_DEFCONFIG := x86_64_defconfig