diff --git a/configs/z80sim/src/Makefile b/configs/z80sim/src/Makefile
index 0410aedf320..0c5e71b255c 100644
--- a/configs/z80sim/src/Makefile
+++ b/configs/z80sim/src/Makefile
@@ -36,6 +36,10 @@
 -include $(TOPDIR)/Make.defs
 
 ASRCS =
-CSRCS = z80_irq.c z80_serial.c z80_timerisr.c z80_lowputc.c
+CSRCS = z80_irq.c z80_timerisr.c z80_lowputc.c
+
+ifneq ($(CONFIG_DISABLE_SIGNALS),y)
+CSRCS += z80_serial.c
+endif
 
 include $(TOPDIR)/configs/Board.mk