diff --git a/conf/any-emu.rmk b/conf/any-emu.rmk
index d3d2c2f2f..a4ee9b755 100644
--- a/conf/any-emu.rmk
+++ b/conf/any-emu.rmk
@@ -1,7 +1,7 @@
 # -*- makefile -*-
 
 COMMON_LDFLAGS += -nostdlib
-COMMON_CFLAGS += -nostdinc -isystem $(shell $(TARGET_CC) -print-file-name=include)
+COMMON_CFLAGS += -nostdinc -isystem $(shell $(TARGET_CC) -print-file-name=include) -fno-builtin
 
 # Used by various components.  These rules need to precede them.
 script/lexer.c_DEPENDENCIES = grub_script.tab.h