diff --git a/byterun/interp.c b/byterun/interp.c
index 810f96984cbe..7cc833af22a2 100644
--- a/byterun/interp.c
+++ b/byterun/interp.c
@@ -89,6 +89,11 @@ extern code_t start_code;
 #define SP_REG asm("%edi")
 #define ACCU_REG
 #endif
+#if defined(PPC) || defined(_POWER) || defined(_IBMR2)
+#define PC_REG asm("31")
+#define SP_REG asm("30")
+#define ACCU_REG asm("29")
+#endif
 #endif
 
 /* The interpreter itself */