diff --git a/arch/mips/momentum/jaguar_atx/prom.c b/arch/mips/momentum/jaguar_atx/prom.c
index 14ae2e7135850..aae7a802767a5 100644
--- a/arch/mips/momentum/jaguar_atx/prom.c
+++ b/arch/mips/momentum/jaguar_atx/prom.c
@@ -236,8 +236,9 @@ void __init prom_init(void)
 #endif
 }
 
-void __init prom_free_prom_memory(void)
+unsigned long __init prom_free_prom_memory(void)
 {
+	return 0;
 }
 
 void __init prom_fixup_mem_map(unsigned long start, unsigned long end)
diff --git a/arch/mips/momentum/ocelot_3/prom.c b/arch/mips/momentum/ocelot_3/prom.c
index c4fa9c525faaa..9803daa2a792f 100644
--- a/arch/mips/momentum/ocelot_3/prom.c
+++ b/arch/mips/momentum/ocelot_3/prom.c
@@ -239,8 +239,9 @@ void __init prom_init(void)
 #endif
 }
 
-void __init prom_free_prom_memory(void)
+unsigned long __init prom_free_prom_memory(void)
 {
+	return 0;
 }
 
 void __init prom_fixup_mem_map(unsigned long start, unsigned long end)
diff --git a/arch/mips/pmc-sierra/yosemite/prom.c b/arch/mips/pmc-sierra/yosemite/prom.c
index 1fb3e697948dd..555bfacf76475 100644
--- a/arch/mips/pmc-sierra/yosemite/prom.c
+++ b/arch/mips/pmc-sierra/yosemite/prom.c
@@ -132,8 +132,9 @@ void __init prom_init(void)
 	prom_grab_secondary();
 }
 
-void __init prom_free_prom_memory(void)
+unsigned long __init prom_free_prom_memory(void)
 {
+	return 0;
 }
 
 void __init prom_fixup_mem_map(unsigned long start, unsigned long end)