diff --git a/rhino/src/main/java/org/mozilla/javascript/ArrayLikeAbstractOperations.java b/rhino/src/main/java/org/mozilla/javascript/ArrayLikeAbstractOperations.java
index e9b0a61d66..5f6e416a5a 100644
--- a/rhino/src/main/java/org/mozilla/javascript/ArrayLikeAbstractOperations.java
+++ b/rhino/src/main/java/org/mozilla/javascript/ArrayLikeAbstractOperations.java
@@ -120,7 +120,8 @@ public static Object iterativeMethod(
                     break;
                 case FIND_INDEX:
                 case FIND_LAST_INDEX:
-                    if (ScriptRuntime.toBoolean(result)) return ScriptRuntime.wrapNumber(i);
+                    if (ScriptRuntime.toBoolean(result))
+                        return ScriptRuntime.wrapNumber((double) i);
                     break;
             }
         }
diff --git a/rhino/src/main/java/org/mozilla/javascript/ScriptRuntime.java b/rhino/src/main/java/org/mozilla/javascript/ScriptRuntime.java
index 27e2c188d4..3dc542f6fe 100644
--- a/rhino/src/main/java/org/mozilla/javascript/ScriptRuntime.java
+++ b/rhino/src/main/java/org/mozilla/javascript/ScriptRuntime.java
@@ -458,7 +458,7 @@ public static double toNumber(Object[] args, int index) {
     // Preserve backward-compatibility with historical value of this.
     public static final double negativeZero = Double.longBitsToDouble(0x8000000000000000L);
 
-    public static final Double zeroObj = Double.valueOf(0.0);
+    public static final Integer zeroObj = Integer.valueOf(0);
     public static final Double negativeZeroObj = Double.valueOf(-0.0);
 
     static double stringPrefixToNumber(String s, int start, int radix) {
@@ -2991,6 +2991,9 @@ public static Object add(Object val1, Object val2, Context cx) {
                 || (val1 instanceof BigInteger && val2 instanceof Number)) {
             throw ScriptRuntime.typeErrorById("msg.cant.convert.to.number", "BigInt");
         }
+        if (val1 instanceof Integer && val2 instanceof Integer) {
+            return add((Integer) val1, (Integer) val2);
+        }
         if (val1 instanceof Number && val2 instanceof Number) {
             return wrapNumber(((Number) val1).doubleValue() + ((Number) val2).doubleValue());
         }
@@ -3064,6 +3067,8 @@ public static Number subtract(Number val1, Number val2) {
             return ((BigInteger) val1).subtract((BigInteger) val2);
         } else if (val1 instanceof BigInteger || val2 instanceof BigInteger) {
             throw ScriptRuntime.typeErrorById("msg.cant.convert.to.number", "BigInt");
+        } else if (val1 instanceof Integer && val2 instanceof Integer) {
+            return subtract((Integer) val1, (Integer) val2);
         } else {
             return val1.doubleValue() - val2.doubleValue();
         }
@@ -3074,6 +3079,8 @@ public static Number multiply(Number val1, Number val2) {
             return ((BigInteger) val1).multiply((BigInteger) val2);
         } else if (val1 instanceof BigInteger || val2 instanceof BigInteger) {
             throw ScriptRuntime.typeErrorById("msg.cant.convert.to.number", "BigInt");
+        } else if (val1 instanceof Integer && val2 instanceof Integer) {
+            return multiply((Integer) val1, (Integer) val2);
         } else {
             return val1.doubleValue() * val2.doubleValue();
         }
@@ -3088,6 +3095,8 @@ public static Number divide(Number val1, Number val2) {
         } else if (val1 instanceof BigInteger || val2 instanceof BigInteger) {
             throw ScriptRuntime.typeErrorById("msg.cant.convert.to.number", "BigInt");
         } else {
+            // Do not try to optimize for the integer case because JS doesn't
+            // have an integer type.
             return val1.doubleValue() / val2.doubleValue();
         }
     }
@@ -3101,10 +3110,41 @@ public static Number remainder(Number val1, Number val2) {
         } else if (val1 instanceof BigInteger || val2 instanceof BigInteger) {
             throw ScriptRuntime.typeErrorById("msg.cant.convert.to.number", "BigInt");
         } else {
+            // Do not try an integer-specific optimization because we need to get
+            // both +0 and -0 right.
             return val1.doubleValue() % val2.doubleValue();
         }
     }
 
+    // Integer-optimized methods.
+
+    public static Object add(Integer i1, Integer i2) {
+        // Try to add integers for efficiency, but account for overflow
+        long r = (long) i1.intValue() + (long) i2.intValue();
+        if ((r >= Integer.MIN_VALUE) && (r <= Integer.MAX_VALUE)) {
+            return Integer.valueOf((int) r);
+        }
+        return Double.valueOf((double) r);
+    }
+
+    public static Number subtract(Integer i1, Integer i2) {
+        // Account for overflow
+        long r = (long) i1.intValue() - (long) i2.intValue();
+        if ((r >= Integer.MIN_VALUE) && (r <= Integer.MAX_VALUE)) {
+            return Integer.valueOf((int) r);
+        }
+        return Double.valueOf((double) r);
+    }
+
+    public static Number multiply(Integer i1, Integer i2) {
+        // Aunt for overflow
+        long r = (long) i1.intValue() * (long) i2.intValue();
+        if ((r >= Integer.MIN_VALUE) && (r <= Integer.MAX_VALUE)) {
+            return Integer.valueOf((int) r);
+        }
+        return Double.valueOf((double) r);
+    }
+
     public static Number exponentiate(Number val1, Number val2) {
         if (val1 instanceof BigInteger && val2 instanceof BigInteger) {
             if (((BigInteger) val2).signum() == -1) {
@@ -3130,6 +3170,8 @@ public static Number bitwiseAND(Number val1, Number val2) {
             return ((BigInteger) val1).and((BigInteger) val2);
         } else if (val1 instanceof BigInteger || val2 instanceof BigInteger) {
             throw ScriptRuntime.typeErrorById("msg.cant.convert.to.number", "BigInt");
+        } else if (val1 instanceof Integer && val2 instanceof Integer) {
+            return Integer.valueOf(((Integer) val1).intValue() & ((Integer) val2).intValue());
         } else {
             int result = toInt32(val1.doubleValue()) & toInt32(val2.doubleValue());
             return Double.valueOf(result);
@@ -3141,6 +3183,8 @@ public static Number bitwiseOR(Number val1, Number val2) {
             return ((BigInteger) val1).or((BigInteger) val2);
         } else if (val1 instanceof BigInteger || val2 instanceof BigInteger) {
             throw ScriptRuntime.typeErrorById("msg.cant.convert.to.number", "BigInt");
+        } else if (val1 instanceof Integer && val2 instanceof Integer) {
+            return Integer.valueOf(((Integer) val1).intValue() | ((Integer) val2).intValue());
         } else {
             int result = toInt32(val1.doubleValue()) | toInt32(val2.doubleValue());
             return Double.valueOf(result);
@@ -3152,6 +3196,8 @@ public static Number bitwiseXOR(Number val1, Number val2) {
             return ((BigInteger) val1).xor((BigInteger) val2);
         } else if (val1 instanceof BigInteger || val2 instanceof BigInteger) {
             throw ScriptRuntime.typeErrorById("msg.cant.convert.to.number", "BigInt");
+        } else if (val1 instanceof Integer && val2 instanceof Integer) {
+            return Integer.valueOf(((Integer) val1).intValue() ^ ((Integer) val2).intValue());
         } else {
             int result = toInt32(val1.doubleValue()) ^ toInt32(val2.doubleValue());
             return Double.valueOf(result);
@@ -3169,6 +3215,8 @@ public static Number leftShift(Number val1, Number val2) {
             }
         } else if (val1 instanceof BigInteger || val2 instanceof BigInteger) {
             throw ScriptRuntime.typeErrorById("msg.cant.convert.to.number", "BigInt");
+        } else if (val1 instanceof Integer && val2 instanceof Integer) {
+            return Integer.valueOf(((Integer) val1).intValue() << ((Integer) val2).intValue());
         } else {
             int result = toInt32(val1.doubleValue()) << toInt32(val2.doubleValue());
             return Double.valueOf(result);
@@ -3186,6 +3234,8 @@ public static Number signedRightShift(Number val1, Number val2) {
             }
         } else if (val1 instanceof BigInteger || val2 instanceof BigInteger) {
             throw ScriptRuntime.typeErrorById("msg.cant.convert.to.number", "BigInt");
+        } else if (val1 instanceof Integer && val2 instanceof Integer) {
+            return Integer.valueOf(((Integer) val1).intValue() >> ((Integer) val2).intValue());
         } else {
             int result = toInt32(val1.doubleValue()) >> toInt32(val2.doubleValue());
             return Double.valueOf(result);
@@ -3195,6 +3245,8 @@ public static Number signedRightShift(Number val1, Number val2) {
     public static Number bitwiseNOT(Number val) {
         if (val instanceof BigInteger) {
             return ((BigInteger) val).not();
+        } else if (val instanceof Integer) {
+            return Integer.valueOf(~((Integer) val).intValue());
         } else {
             int result = ~toInt32(val.doubleValue());
             return Double.valueOf(result);
@@ -3292,6 +3344,12 @@ private static Object doScriptableIncrDecr(
             } else {
                 result = ((BigInteger) number).subtract(BigInteger.ONE);
             }
+        } else if (number instanceof Integer) {
+            if ((incrDecrMask & Node.DECR_FLAG) == 0) {
+                result = ((Integer) number).intValue() + 1;
+            } else {
+                result = ((Integer) number).intValue() - 1;
+            }
         } else {
             if ((incrDecrMask & Node.DECR_FLAG) == 0) {
                 result = number.doubleValue() + 1.0;
@@ -3332,6 +3390,12 @@ public static Object elemIncrDecr(
             } else {
                 result = ((BigInteger) number).subtract(BigInteger.ONE);
             }
+        } else if (number instanceof Integer) {
+            if ((incrDecrMask & Node.DECR_FLAG) == 0) {
+                result = ((Integer) number).intValue() + 1;
+            } else {
+                result = ((Integer) number).intValue() - 1;
+            }
         } else {
             if ((incrDecrMask & Node.DECR_FLAG) == 0) {
                 result = number.doubleValue() + 1.0;
@@ -3371,6 +3435,12 @@ public static Object refIncrDecr(Ref ref, Context cx, Scriptable scope, int incr
             } else {
                 result = ((BigInteger) number).subtract(BigInteger.ONE);
             }
+        } else if (number instanceof Integer) {
+            if ((incrDecrMask & Node.DECR_FLAG) == 0) {
+                result = ((Integer) number).intValue() + 1;
+            } else {
+                result = ((Integer) number).intValue() - 1;
+            }
         } else {
             if ((incrDecrMask & Node.DECR_FLAG) == 0) {
                 result = number.doubleValue() + 1.0;
@@ -3390,6 +3460,17 @@ public static Number negate(Number val) {
         if (val instanceof BigInteger) {
             return ((BigInteger) val).negate();
         }
+        if (val instanceof Integer) {
+            int iv = (Integer) val;
+            if (iv == 0) {
+                return negativeZeroObj;
+            }
+            if (iv > Integer.MIN_VALUE && iv < Integer.MAX_VALUE) {
+                // Account for twos-complement representation by not trying
+                // to negate values at the extremes
+                return Integer.valueOf(-((Integer) val).intValue());
+            }
+        }
         return -val.doubleValue();
     }
 
diff --git a/rhino/src/main/java/org/mozilla/javascript/optimizer/Codegen.java b/rhino/src/main/java/org/mozilla/javascript/optimizer/Codegen.java
index bfe7e112c2..4062d7ccf3 100644
--- a/rhino/src/main/java/org/mozilla/javascript/optimizer/Codegen.java
+++ b/rhino/src/main/java/org/mozilla/javascript/optimizer/Codegen.java
@@ -1143,7 +1143,7 @@ void pushNumberAsObject(ClassFileWriter cfw, double num) {
                         ByteCode.GETSTATIC,
                         "org/mozilla/javascript/ScriptRuntime",
                         "zeroObj",
-                        "Ljava/lang/Double;");
+                        "Ljava/lang/Integer;");
             } else {
                 cfw.addPush(num);
                 addDoubleWrap(cfw);
@@ -1154,7 +1154,7 @@ void pushNumberAsObject(ClassFileWriter cfw, double num) {
                     ByteCode.GETSTATIC,
                     "org/mozilla/javascript/optimizer/OptRuntime",
                     "oneObj",
-                    "Ljava/lang/Double;");
+                    "Ljava/lang/Integer;");
             return;
 
         } else if (num == -1.0) {
@@ -1162,7 +1162,7 @@ void pushNumberAsObject(ClassFileWriter cfw, double num) {
                     ByteCode.GETSTATIC,
                     "org/mozilla/javascript/optimizer/OptRuntime",
                     "minusOneObj",
-                    "Ljava/lang/Double;");
+                    "Ljava/lang/Integer;");
 
         } else if (Double.isNaN(num)) {
             cfw.add(
diff --git a/rhino/src/main/java/org/mozilla/javascript/optimizer/OptRuntime.java b/rhino/src/main/java/org/mozilla/javascript/optimizer/OptRuntime.java
index 4452dac468..6e117874fd 100644
--- a/rhino/src/main/java/org/mozilla/javascript/optimizer/OptRuntime.java
+++ b/rhino/src/main/java/org/mozilla/javascript/optimizer/OptRuntime.java
@@ -21,8 +21,8 @@
 import org.mozilla.javascript.Undefined;
 
 public final class OptRuntime extends ScriptRuntime {
-    public static final Double oneObj = Double.valueOf(1.0);
-    public static final Double minusOneObj = Double.valueOf(-1.0);
+    public static final Integer oneObj = Integer.valueOf(1);
+    public static final Integer minusOneObj = Integer.valueOf(-1);
 
     /** Implement ....() call shrinking optimizer code. */
     public static Object call0(Callable fun, Scriptable thisObj, Context cx, Scriptable scope) {
@@ -145,16 +145,7 @@ public static Object newObjectSpecial(
     }
 
     public static Double wrapDouble(double num) {
-        if (num == 0.0) {
-            if (1 / num > 0) {
-                // +0.0
-                return zeroObj;
-            }
-        } else if (num == 1.0) {
-            return oneObj;
-        } else if (num == -1.0) {
-            return minusOneObj;
-        } else if (Double.isNaN(num)) {
+        if (Double.isNaN(num)) {
             return NaNobj;
         }
         return Double.valueOf(num);
diff --git a/rhino/src/test/java/org/mozilla/javascript/tests/Bug687669Test.java b/rhino/src/test/java/org/mozilla/javascript/tests/Bug687669Test.java
index 6a7d223907..927787da25 100644
--- a/rhino/src/test/java/org/mozilla/javascript/tests/Bug687669Test.java
+++ b/rhino/src/test/java/org/mozilla/javascript/tests/Bug687669Test.java
@@ -56,9 +56,9 @@ private String toSource(CharSequence cs) {
     public void eval() {
         // test EmptyStatement node doesn't infer with return values (in
         // contrast to wrapping EmptyExpression into an ExpressionStatement)
-        assertEquals(1d, eval("1;;;;"));
+        assertEquals(1, eval("1;;;;"));
         assertEquals(Undefined.instance, eval("(function(){1;;;;})()"));
-        assertEquals(1d, eval("(function(){return 1;;;;})()"));
+        assertEquals(1, eval("(function(){return 1;;;;})()"));
     }
 
     @Test
diff --git a/rhino/src/test/java/org/mozilla/javascript/tests/DefineFunctionPropertiesTest.java b/rhino/src/test/java/org/mozilla/javascript/tests/DefineFunctionPropertiesTest.java
index a7d13ae706..f9bda83c15 100644
--- a/rhino/src/test/java/org/mozilla/javascript/tests/DefineFunctionPropertiesTest.java
+++ b/rhino/src/test/java/org/mozilla/javascript/tests/DefineFunctionPropertiesTest.java
@@ -48,7 +48,7 @@ public static int f(int a) {
     public void simpleFunction() {
         try (Context cx = Context.enter()) {
             Object result = cx.evaluateString(global, "f(7) + 1", "test source", 1, null);
-            assertEquals(15.0, result);
+            assertEquals(15, result);
         }
     }
 
diff --git a/tests/src/test/java/org/mozilla/javascript/tests/NativeConsoleTest.java b/tests/src/test/java/org/mozilla/javascript/tests/NativeConsoleTest.java
index bed2726da5..016b6d74dd 100644
--- a/tests/src/test/java/org/mozilla/javascript/tests/NativeConsoleTest.java
+++ b/tests/src/test/java/org/mozilla/javascript/tests/NativeConsoleTest.java
@@ -440,8 +440,7 @@ public void testAssert() {
         assertPrintCalls(
                 "console.assert(false, 'Fail', 1)",
                 Collections.singletonList(
-                        new PrinterCall(
-                                Level.ERROR, new Object[] {"Assertion failed: Fail", 1.0})));
+                        new PrinterCall(Level.ERROR, new Object[] {"Assertion failed: Fail", 1})));
         assertPrintMsg("console.assert(false, 'Fail', 1)", "Assertion failed: Fail 1");
 
         assertPrintCalls(