diff --git a/unix/Makefile b/unix/Makefile
index a6b5026e21..8ee2319828 100644
--- a/unix/Makefile
+++ b/unix/Makefile
@@ -44,6 +44,8 @@ endif
 LDFLAGS = $(LDFLAGS_MOD) $(LDFLAGS_ARCH) -lm $(LDFLAGS_EXTRA)
 
 ifeq ($(MICROPY_FORCE_32BIT),1)
+# Note: you may need to install i386 versions of dependency packages,
+# starting with linux-libc-dev:i386
 CFLAGS += -m32
 LDFLAGS += -m32
 ifeq ($(MICROPY_PY_FFI),1)