diff --git a/cpu/msp430/Makefile.msp430 b/cpu/msp430/Makefile.msp430
index 7d71d4029..4057b3c5a 100644
--- a/cpu/msp430/Makefile.msp430
+++ b/cpu/msp430/Makefile.msp430
@@ -166,8 +166,8 @@ loader-init.o: ${CONTIKI_TARGET}/loader/loader-init.S
 	$(AS) -o $(notdir $(<:.S=.o)) $<
 # 	cp loader-init.o build-app/
 
-.PHONY: symbols.c symbols.h
 ifdef CORE
+.PHONY: symbols.c symbols.h
 symbols.c:
 	$(NM) $(CORE) | awk -f $(CONTIKI)/tools/mknmlist > symbols.c
 else
diff --git a/cpu/stm32w108/Makefile.stm32w108 b/cpu/stm32w108/Makefile.stm32w108
index 7eae06d4c..8fbb1e9b6 100644
--- a/cpu/stm32w108/Makefile.stm32w108
+++ b/cpu/stm32w108/Makefile.stm32w108
@@ -224,11 +224,11 @@ CUSTOM_RULE_C_TO_CE = 1
 
 CUSTOM_RULE_LINK = 1
 
-.PHONY: symbols.c symbols.h
 ifdef CORE
 ifeq ($(wildcard $(CORE)),)
  ${error $(CORE) doesn't exist}
 endif
+.PHONY: symbols.c symbols.h
 symbols.c:
 	$(NM) $(CORE) | awk -f $(CONTIKI)/tools/mknmlist > symbols.c	
 else
diff --git a/cpu/x86/Makefile.x86 b/cpu/x86/Makefile.x86
index 612603f52..0aececd4d 100644
--- a/cpu/x86/Makefile.x86
+++ b/cpu/x86/Makefile.x86
@@ -21,8 +21,8 @@ endif
 %.so: $(OBJECTDIR)/%.o
 	$(LD) -shared -o $@ $^
 
-# .PHONY: symbols.c symbols.h
 ifdef CORE
+.PHONY: symbols.c symbols.h
 symbols.c symbols.h:
 	$(NM) $(CORE) | awk -f $(CONTIKI)/tools/mknmlist > symbols.c
 else