diff --git a/basis/cpu/ppc/ppc.factor b/basis/cpu/ppc/ppc.factor
index 6b51585750..46986dc5e6 100644
--- a/basis/cpu/ppc/ppc.factor
+++ b/basis/cpu/ppc/ppc.factor
@@ -139,9 +139,9 @@ M:: ppc %string-nth ( dst src index temp -- )
         "end" define-label
         temp src index ADD
         dst temp string-offset LBZ
+        0 dst HEX: 80 CMPI
+        "end" get BLT
         temp src string-aux-offset LWZ
-        0 temp \ f tag-number CMPI
-        "end" get BEQ
         temp temp index ADD
         temp temp index ADD
         temp temp byte-array-offset LHZ
@@ -150,6 +150,10 @@ M:: ppc %string-nth ( dst src index temp -- )
         "end" resolve-label
     ] with-scope ;
 
+M:: ppc %set-string-nth-fast ( ch obj index temp -- )
+    temp obj index ADD
+    ch temp string-offset STB ;
+
 M: ppc %add     ADD ;
 M: ppc %add-imm ADDI ;
 M: ppc %sub     swap SUBF ;