diff --git a/core/envsetup.mk b/core/envsetup.mk
index 3dfcfd686..ee04557e5 100644
--- a/core/envsetup.mk
+++ b/core/envsetup.mk
@@ -72,6 +72,10 @@ ifneq (,$(findstring x86_64,$(UNAME)))
   HOST_ARCH := x86_64
   HOST_2ND_ARCH := x86
   HOST_IS_64_BIT := true
+else
+ifneq (,$(findstring x86,$(UNAME)))
+$(error Building on a 32-bit x86 host is not supported: $(UNAME)!)
+endif
 endif
 
 BUILD_ARCH := $(HOST_ARCH)