diff --git a/js/src/jit-test/tests/jaeger/bug655810.js b/js/src/jit-test/tests/jaeger/bug655810.js
new file mode 100644
index 00000000000..e31d56234c3
--- /dev/null
+++ b/js/src/jit-test/tests/jaeger/bug655810.js
@@ -0,0 +1,6 @@
+function f(arr) {
+    var x = arr[0];
+    if (typeof x) {};
+    Math.abs(x);
+}
+f([1.2]);
diff --git a/js/src/methodjit/MachineRegs.h b/js/src/methodjit/MachineRegs.h
index 9aaddf66c3c..f1064debf39 100644
--- a/js/src/methodjit/MachineRegs.h
+++ b/js/src/methodjit/MachineRegs.h
@@ -434,10 +434,9 @@ struct Registers {
 
     AnyRegisterID peekReg(uint32 mask) {
         JS_ASSERT(!empty(mask));
-        int ireg;
+        unsigned ireg;
         JS_FLOOR_LOG2(ireg, freeMask & mask);
-        RegisterID reg = (RegisterID)ireg;
-        return reg;
+        return AnyRegisterID::fromRaw(ireg);
     }
 
     AnyRegisterID peekReg() {