diff --git a/src/stub/src/arch/powerpc/32/ppc_regs.h b/src/stub/src/arch/powerpc/32/ppc_regs.h
index 939137d2..c207e677 100644
--- a/src/stub/src/arch/powerpc/32/ppc_regs.h
+++ b/src/stub/src/arch/powerpc/32/ppc_regs.h
@@ -5,6 +5,8 @@
 #define r1 1
 #define r2 2
 
+#define r27 27
+#define r28 28
 #define r29 29
 #define r30 30
 #define r31 31
@@ -27,6 +29,8 @@
 #define t1 11
 #define t2 12
 #define t3 13
+/* t4 is unofficial? */
+#define t4 14
 
 /* branch and link */
 #define call bl