diff --git a/js/src/ion/MIR.h b/js/src/ion/MIR.h
index 220e15048443..8b3b1ae00e7c 100644
--- a/js/src/ion/MIR.h
+++ b/js/src/ion/MIR.h
@@ -2755,9 +2755,9 @@ class MBeta : public MUnaryInstruction
   private:
     Range comparison_;
     MDefinition *val_;
-    MBeta(MDefinition *val, int32 low, int32 high)
+    MBeta(MDefinition *val, const Range &comp)
         : MUnaryInstruction(val),
-          comparison_(low, high),
+          comparison_(comp),
           val_(val)
     {
     }
@@ -2765,9 +2765,9 @@ class MBeta : public MUnaryInstruction
   public:
     INSTRUCTION_HEADER(Beta);
     void printOpcode(FILE *fp);
-    static MBeta *New(MDefinition *val, int32 low, int32 high)
+    static MBeta *New(MDefinition *val, const Range &comp)
     {
-        return new MBeta(val, low, high);
+        return new MBeta(val, comp);
     }
 
     AliasSet getAliasSet() const {
diff --git a/js/src/ion/RangeAnalysis.cpp b/js/src/ion/RangeAnalysis.cpp
index e467b4a48fc0..0ea252cd5d50 100644
--- a/js/src/ion/RangeAnalysis.cpp
+++ b/js/src/ion/RangeAnalysis.cpp
@@ -162,10 +162,10 @@ RangeAnalysis::addBetaNobes()
             }
             if (smaller && greater) {
                 MBeta *beta;
-                beta = MBeta::New(smaller, JSVAL_INT_MIN, JSVAL_INT_MAX-1);
+                beta = MBeta::New(smaller, Range(JSVAL_INT_MIN, JSVAL_INT_MAX-1));
                 block->insertBefore(*block->begin(), beta);
                 replaceDominatedUsesWith(smaller, beta, block);
-                beta = MBeta::New(greater, JSVAL_INT_MIN+1, JSVAL_INT_MAX);
+                beta = MBeta::New(greater, Range(JSVAL_INT_MIN+1, JSVAL_INT_MAX));
                 block->insertBefore(*block->begin(), beta);
                 replaceDominatedUsesWith(greater, beta, block);
             }
@@ -175,35 +175,34 @@ RangeAnalysis::addBetaNobes()
         JS_ASSERT(val);
 
 
-        int32 low = JSVAL_INT_MIN;
-        int32 high = JSVAL_INT_MAX;
+        Range comp;
         switch (jsop) {
           case JSOP_LE:
-            high = bound;
+            comp.setUpper(bound);
             break;
           case JSOP_LT:
             if (!SafeSub(bound, 1, &bound))
                 break;
-            high = bound;
+            comp.setUpper(bound);
             break;
           case JSOP_GE:
-            low = bound;
+            comp.setLower(bound);
             break;
           case JSOP_GT:
             if (!SafeAdd(bound, 1, &bound))
                 break;
-            low = bound;
+            comp.setLower(bound);
             break;
           case JSOP_EQ:
-            low = bound;
-            high = bound;
+            comp.setLower(bound);
+            comp.setUpper(bound);
           default:
             break; // well, for neq we could have
                    // [-\inf, bound-1] U [bound+1, \inf] but we only use contiguous ranges.
         }
 
         IonSpew(IonSpew_Range, "Adding beta node for %d", val->id());
-        MBeta *beta = MBeta::New(val, low, high);
+        MBeta *beta = MBeta::New(val, comp);
         block->insertBefore(*block->begin(), beta);
         replaceDominatedUsesWith(val, beta, block);
     }
@@ -290,17 +289,20 @@ Range::unionWith(const Range *other)
 Range
 Range::add(const Range *lhs, const Range *rhs)
 {
-    return Range(
+    Range ret(
         (int64_t)lhs->lower_ + (int64_t)rhs->lower_,
         (int64_t)lhs->upper_ + (int64_t)rhs->upper_);
+    return ret;
 }
 
 Range
 Range::sub(const Range *lhs, const Range *rhs)
 {
-    return Range(
+    Range ret(
         (int64_t)lhs->lower_ - (int64_t)rhs->upper_,
         (int64_t)lhs->upper_ - (int64_t)rhs->lower_);
+    return ret;
+
 }
 
 Range
@@ -310,27 +312,30 @@ Range::mul(const Range *lhs, const Range *rhs)
     int64_t b = (int64_t)lhs->lower_ * (int64_t)rhs->upper_;
     int64_t c = (int64_t)lhs->upper_ * (int64_t)rhs->lower_;
     int64_t d = (int64_t)lhs->upper_ * (int64_t)rhs->upper_;
-    return Range(
+    Range ret(
         Min( Min(a, b), Min(c, d) ),
         Max( Max(a, b), Max(c, d) ));
+    return ret;
 }
 
 Range
 Range::shl(const Range *lhs, int32 c)
 {
     int32 shift = c & 0x1f;
-    return Range(
+    Range ret(
         (int64_t)lhs->lower_ << shift,
         (int64_t)lhs->upper_ << shift);
+    return ret;
 }
 
 Range
 Range::shr(const Range *lhs, int32 c)
 {
     int32 shift = c & 0x1f;
-    return Range(
+    Range ret(
         (int64_t)lhs->lower_ >> shift,
         (int64_t)lhs->upper_ >> shift);
+    return ret;
 }
 
 bool
diff --git a/js/src/ion/RangeAnalysis.h b/js/src/ion/RangeAnalysis.h
index 9ddff2d85858..aa70452dd88a 100644
--- a/js/src/ion/RangeAnalysis.h
+++ b/js/src/ion/RangeAnalysis.h
@@ -69,8 +69,8 @@ class Range {
         bool upper_infinite_;
 
     public:
-        Range() :
-            lower_(JSVAL_INT_MIN),
+        Range()
+          : lower_(JSVAL_INT_MIN),
             lower_infinite_(true),
             upper_(JSVAL_INT_MAX),
             upper_infinite_(true)
@@ -81,6 +81,13 @@ class Range {
             setUpper(h);
         }
 
+        Range(const Range &other)
+          : lower_(other.lower_),
+            lower_infinite_(other.lower_infinite_),
+            upper_(other.upper_),
+            upper_infinite_(other.upper_infinite_)
+        {}
+
         static int64_t abs64(int64_t x) {
 #ifdef WTF_OS_WINDOWS
             return _abs64(x);