diff --git a/lib/lpc13xx/Makefile b/lib/lpc13xx/Makefile
index 35f27a3f..7d12597e 100644
--- a/lib/lpc13xx/Makefile
+++ b/lib/lpc13xx/Makefile
@@ -33,7 +33,8 @@ TGT_CFLAGS      += $(DEBUG_FLAGS)
 TGT_CFLAGS	+= $(STANDARD_FLAGS)
 # ARFLAGS	= rcsv
 ARFLAGS		= rcs
-OBJS		= gpio.o
+
+OBJS += gpio.o
 
 VPATH += ../cm3
 
diff --git a/lib/lpc17xx/Makefile b/lib/lpc17xx/Makefile
index c970bea1..eaaef8c8 100644
--- a/lib/lpc17xx/Makefile
+++ b/lib/lpc17xx/Makefile
@@ -33,7 +33,9 @@ TGT_CFLAGS      += $(DEBUG_FLAGS)
 TGT_CFLAGS	+= $(STANDARD_FLAGS)
 # ARFLAGS	= rcsv
 ARFLAGS		= rcs
-OBJS		= gpio.o pwr.o
+
+OBJS += gpio.o
+OBJS += pwr.o
 
 VPATH += ../cm3