diff --git a/core/clang/config.mk b/core/clang/config.mk
index 11253688a..1de46f000 100644
--- a/core/clang/config.mk
+++ b/core/clang/config.mk
@@ -24,9 +24,13 @@ CLANG_CONFIG_EXTRA_CFLAGS :=
 CLANG_CONFIG_EXTRA_CPPFLAGS :=
 CLANG_CONFIG_EXTRA_LDFLAGS :=
 
-CLANG_CONFIG_EXTRA_CFLAGS := \
+CLANG_CONFIG_EXTRA_CFLAGS += \
   -D__compiler_offsetof=__builtin_offsetof
 
+# Help catch common 32/64-bit errors.
+CLANG_CONFIG_EXTRA_CFLAGS += \
+  -Werror=int-conversion
+
 CLANG_CONFIG_UNKNOWN_CFLAGS := \
   -funswitch-loops \
   -fno-tree-sra \