diff --git a/cpu/cc2538/Makefile.cc2538 b/cpu/cc2538/Makefile.cc2538
index 29795111c..56ce4a2c9 100644
--- a/cpu/cc2538/Makefile.cc2538
+++ b/cpu/cc2538/Makefile.cc2538
@@ -70,6 +70,8 @@ CPU_STARTFILES = ${addprefix $(OBJECTDIR)/,${call oname, $(CPU_START_SOURCEFILES
 CONTIKI_SOURCEFILES += $(CONTIKI_CPU_SOURCEFILES) $(DEBUG_IO_SOURCEFILES)
 CONTIKI_SOURCEFILES += $(USB_CORE_SOURCEFILES) $(USB_ARCH_SOURCEFILES)
 
+.SECONDEXPANSION:
+
 ### Don't treat the .elf as intermediate
 .PRECIOUS: %.elf %.hex %.bin
 
@@ -83,7 +85,7 @@ $(OBJECTDIR)/ieee-addr.o: ieee-addr.c FORCE | $(OBJECTDIR)
 ### Compilation rules
 CUSTOM_RULE_LINK=1
 
-%.elf: $(CPU_STARTFILES) %.co $(PROJECT_OBJECTFILES) $(PROJECT_LIBRARIES) contiki-$(TARGET).a $(LDSCRIPT)
+%.elf: $(CPU_STARTFILES) $$(CONTIKI_OBJECTFILES) %.co $(PROJECT_OBJECTFILES) $(PROJECT_LIBRARIES) $(LDSCRIPT)
 	$(TRACE_LD)
 	$(Q)$(LD) $(LDFLAGS) ${filter-out $(LDSCRIPT) %.a,$^} ${filter %.a,$^} $(TARGET_LIBFILES) -o $@
 
diff --git a/cpu/cc2538/startup-gcc.c b/cpu/cc2538/startup-gcc.c
index 2aa82894e..944c6a6e9 100644
--- a/cpu/cc2538/startup-gcc.c
+++ b/cpu/cc2538/startup-gcc.c
@@ -46,8 +46,6 @@
 /*---------------------------------------------------------------------------*/
 extern int main(void);
 /*---------------------------------------------------------------------------*/
-#define WEAK_ALIAS(x) __attribute__ ((weak, alias(#x)))
-/*---------------------------------------------------------------------------*/
 /* System handlers provided here */
 void reset_handler(void);
 void nmi_handler(void);
@@ -64,11 +62,24 @@ void cc2538_rf_rx_tx_isr(void);
 void cc2538_rf_err_isr(void);
 void udma_isr(void);
 void udma_err_isr(void);
-void usb_isr(void) WEAK_ALIAS(default_handler);
-void uart0_isr(void) WEAK_ALIAS(default_handler);
-void uart1_isr(void) WEAK_ALIAS(default_handler);
 void crypto_isr(void);
 
+/* Link in the USB ISR only if USB is enabled */
+#if USB_SERIAL_CONF_ENABLE
+void usb_isr(void);
+#else
+#define usb_isr default_handler
+#endif
+
+/* Likewise for the UART[01] ISRs */
+#if UART_CONF_ENABLE
+void uart0_isr(void);
+void uart1_isr(void);
+#else /* UART_CONF_ENABLE */
+#define uart0_isr default_handler
+#define uart1_isr default_handler
+#endif /* UART_CONF_ENABLE */
+
 /* Boot Loader Backdoor selection */
 #if FLASH_CCA_CONF_BOOTLDR_BACKDOOR
 /* Backdoor enabled */