diff --git a/src/runtime/sys_linux_ppc64x.s b/src/runtime/sys_linux_ppc64x.s
index a40fe3b..2b2aa61 100644
--- a/src/runtime/sys_linux_ppc64x.s
+++ b/src/runtime/sys_linux_ppc64x.s
@@ -21,6 +21,7 @@
 #define SYS_close		  6
 #define SYS_getpid		 20
 #define SYS_kill		 37
+#define SYS_brk			 45
 #define SYS_fcntl		 55
 #define SYS_gettimeofday	 78
 #define SYS_select		 82	// always return -ENOSYS
@@ -157,8 +158,8 @@
 	MOVW	R3, ret+24(FP)
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB),NOSPLIT,$16
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB),NOSPLIT,$16
 	MOVD	$0, R3 // CLOCK_REALTIME
 	MOVD	$0(R1), R4
 	SYSCALL	$SYS_clock_gettime
@@ -189,7 +190,7 @@
 	MOVW	size+24(FP), R6
 	SYSCALL	$SYS_rt_sigprocmask
 	BVC	2(PC)
-	MOVD	R0, 0xf1(R0)	// crash
+	MOVD	R0, 0xf0(R0)	// crash
 	RET
 
 TEXT runtime·rt_sigaction(SB),NOSPLIT|NOFRAME,$0-36
@@ -273,7 +274,7 @@
 	MOVD	n+8(FP), R4
 	SYSCALL	$SYS_munmap
 	BVC	2(PC)
-	MOVD	R0, 0xf3(R0)
+	MOVD	R0, 0xf0(R0)
 	RET
 
 TEXT runtime·madvise(SB),NOSPLIT|NOFRAME,$0
@@ -366,7 +367,7 @@
 	MOVD	old+8(FP), R4
 	SYSCALL	$SYS_sigaltstack
 	BVC	2(PC)
-	MOVD	R0, 0xf1(R0)  // crash
+	MOVD	R0, 0xf0(R0)  // crash
 	RET
 
 TEXT runtime·osyield(SB),NOSPLIT|NOFRAME,$0
@@ -422,3 +423,11 @@
 	MOVD    $1, R5  // FD_CLOEXEC
 	SYSCALL	$SYS_fcntl
 	RET
+
+// func sbrk0() uintptr
+TEXT runtime·sbrk0(SB),NOSPLIT|NOFRAME,$0
+	// Implemented as brk(NULL).
+	MOVD	$0, R3
+	SYSCALL	$SYS_brk
+	MOVD	R3, ret+0(FP)
+	RET