diff --git a/configs/qemu-i486/ostest/Make.defs b/configs/qemu-i486/ostest/Make.defs
index 72f26452bb..e2ac40b09f 100644
--- a/configs/qemu-i486/ostest/Make.defs
+++ b/configs/qemu-i486/ostest/Make.defs
@@ -71,7 +71,7 @@ ARCHDEFINES =
 
 # Check if building a 32-bit target with a 64-bit toolchain
 
-ifeq ($(ARCH_X86_M32),y)
+ifeq ($(CONFIG_ARCH_X86_M32),y)
 ARCHCPUFLAGS += -m32
 endif