diff --git a/src/main.mk b/src/main.mk
index 9818cbd..1c248b8 100644
--- a/src/main.mk
+++ b/src/main.mk
@@ -10,7 +10,7 @@
 # This file is included by primary Makefile.
 #
 
-XBCC = $(BCC) $(BCCFLAGS)
+XBCC = $(BCC) -Os
 XTCC = $(TCC) -I. -I$(SRCDIR) -I$(OBJDIR) $(TCCFLAGS)
 
 TESTFLAGS := -quiet