diff --git a/zipl/boot/libc.h b/zipl/boot/libc.h
index 9cf3b485..f85f5a72 100644
--- a/zipl/boot/libc.h
+++ b/zipl/boot/libc.h
@@ -61,7 +61,7 @@ unsigned long get_zeroed_page(void);
 void free_page(unsigned long);
 void initialize(void);
 void libc_stop(unsigned long) __noreturn;
-void start(void);
+void __noreturn start(void);
 void pgm_check_handler(void);
 void pgm_check_handler_fn(void);
 void panic_notify(unsigned long reason);
diff --git a/zipl/boot/stage2.c b/zipl/boot/stage2.c
index 2353baf5..336713b5 100644
--- a/zipl/boot/stage2.c
+++ b/zipl/boot/stage2.c
@@ -75,15 +75,16 @@ out_free_page:
 }
 
 
-static void execute(uint64_t psw)
+static __noreturn void execute(uint64_t psw)
 {
 	asm volatile(
 		"      lpsw    %[psw]\n"
 		: : [psw] "Q" (psw) : "cc"
 		);
+	__builtin_unreachable();
 }
 
-void start(void)
+void __noreturn start(void)
 {
 	struct stage2_descr stage2_descr;
 	struct subchannel_id subchannel_id;
diff --git a/zipl/boot/stage2dump.c b/zipl/boot/stage2dump.c
index 9ba5d485..05fe290a 100644
--- a/zipl/boot/stage2dump.c
+++ b/zipl/boot/stage2dump.c
@@ -393,7 +393,7 @@ static void store_status(void)
  * Block followed by a valid checksum (as defined in lowcore.h and set
  * by ipl.c). In case of match use diag308 to IPL.
  */
-static void dump_exit(unsigned long code)
+static __noreturn void dump_exit(unsigned long code)
 {
 	struct ipib_info *ipib_info = (struct ipib_info *)&S390_lowcore.ipib;
 	uint32_t ipib_len, csum;
@@ -406,6 +406,7 @@ static void dump_exit(unsigned long code)
 		libc_stop(code);
 	diag308(DIAG308_SET, (void *) ipib_info->ipib);
 	diag308(DIAG308_IPL, NULL);
+	__builtin_unreachable();
 }
 
 /*
@@ -420,7 +421,7 @@ void panic_notify(unsigned long code)
 /*
  * Create stand-alone dump
  */
-void start(void)
+void __noreturn start(void)
 {
 	init_early();
 	dt_device_parm_setup();