diff --git a/rocky.jar b/rocky.jar
index 51fcd42..6502fa0 100644
Binary files a/rocky.jar and b/rocky.jar differ
diff --git a/src/rockstar/expression/NotExpression.java b/src/rockstar/expression/NotExpression.java
index f3bb930..83c74a4 100644
--- a/src/rockstar/expression/NotExpression.java
+++ b/src/rockstar/expression/NotExpression.java
@@ -33,7 +33,7 @@ public Value evaluate(BlockContext ctx) {
         ctx.beforeExpression(this);
         Expression expr = this.getParameters().get(0);
         Value v = expr.evaluate(ctx);
-        return ctx.afterExpression(this, v.negate());
+        return ctx.afterExpression(this, v.negateBoolean());
     }
     
     @Override
diff --git a/src/rockstar/expression/UnaryMinusExpression.java b/src/rockstar/expression/UnaryMinusExpression.java
index df961fc..d82b12b 100644
--- a/src/rockstar/expression/UnaryMinusExpression.java
+++ b/src/rockstar/expression/UnaryMinusExpression.java
@@ -33,7 +33,7 @@ public Value evaluate(BlockContext ctx) {
         ctx.beforeExpression(this);
         Expression expr1 = this.getParameters().get(0);
         Value v1 = expr1.evaluate(ctx);
-        return ctx.afterExpression(this, Value.NULL.minus(v1));
+        return ctx.afterExpression(this, v1.negateNumeric());
     }
     
     @Override
diff --git a/src/rockstar/runtime/RockNumber.java b/src/rockstar/runtime/RockNumber.java
index bb2c216..ed18546 100644
--- a/src/rockstar/runtime/RockNumber.java
+++ b/src/rockstar/runtime/RockNumber.java
@@ -90,4 +90,6 @@ public static RockNumber getValueFromLong(long l) {
     public abstract RockNumber floor();
     public abstract RockNumber round();
 
+	protected abstract RockNumber negate();
+
 }
diff --git a/src/rockstar/runtime/RockNumberBigDecimal.java b/src/rockstar/runtime/RockNumberBigDecimal.java
index feecf94..fba2f60 100644
--- a/src/rockstar/runtime/RockNumberBigDecimal.java
+++ b/src/rockstar/runtime/RockNumberBigDecimal.java
@@ -96,6 +96,7 @@ public boolean isNegative() {
         return value.compareTo(ZERO.value) < 0;
     }
     
+    @Override
     public RockNumberBigDecimal negate() {
         return create(value.negate());
     }
diff --git a/src/rockstar/runtime/RockNumberDec64.java b/src/rockstar/runtime/RockNumberDec64.java
index b267497..0d40481 100644
--- a/src/rockstar/runtime/RockNumberDec64.java
+++ b/src/rockstar/runtime/RockNumberDec64.java
@@ -255,6 +255,7 @@ public boolean isNegative() {
         return mantissa>=0;
     }
     
+    @Override
     public RockNumberDec64 negate() {
         return getFromCache(-mantissa, exponent);
     }
diff --git a/src/rockstar/runtime/RockNumberDouble.java b/src/rockstar/runtime/RockNumberDouble.java
index fdec8e3..4164f6f 100644
--- a/src/rockstar/runtime/RockNumberDouble.java
+++ b/src/rockstar/runtime/RockNumberDouble.java
@@ -16,6 +16,9 @@ public class RockNumberDouble extends RockNumber {
     public final Double dblValue;
 
     private RockNumberDouble(Double dblValue) {
+    	if (dblValue != null && dblValue == -0.0) {
+    		dblValue = 0.0;
+    	}
         this.dblValue = dblValue;
     }
 
@@ -94,6 +97,11 @@ public RockNumberDouble multiply(RockNumber rn) {
     public RockNumberDouble divide(RockNumber rn) {
         return new RockNumberDouble(dblValue / convertToDbl(rn));
     }
+    
+    @Override
+    protected RockNumber negate() {
+    	return new RockNumberDouble(-dblValue);
+    }
 
     @Override
     public int asInt() {
@@ -164,6 +172,5 @@ public RockNumber floor() {
     public RockNumber round() {
         return new RockNumberDouble((double)Math.round(dblValue));
     }
-
     
 }
diff --git a/src/rockstar/runtime/Value.java b/src/rockstar/runtime/Value.java
index d7020f1..e0c4c6f 100644
--- a/src/rockstar/runtime/Value.java
+++ b/src/rockstar/runtime/Value.java
@@ -381,9 +381,17 @@ public String describe() {
         return null;
     }
 
-    public Value negate() {
-        // bool negation
-        return getBool() ? BOOLEAN_FALSE : BOOLEAN_TRUE;
+    public Value negateBoolean() {
+    	return getBool() ? BOOLEAN_FALSE : BOOLEAN_TRUE;
+    }
+
+    public Value negateNumeric() {
+        switch (this.type) {
+        case NUMBER:
+        	return Value.getValue(getNumeric().negate());
+        default:
+        	throw new RockstarRuntimeException("Cannot negate "+this.getType()+" type");
+        }
     }
 
     public Value plus(Value other) {
diff --git a/src/rockstar/statement/DecrementStatement.java b/src/rockstar/statement/DecrementStatement.java
index edbfd5a..9e1c8f8 100644
--- a/src/rockstar/statement/DecrementStatement.java
+++ b/src/rockstar/statement/DecrementStatement.java
@@ -58,7 +58,7 @@ public void execute(BlockContext ctx) {
             v = v.asBoolean();
             if (count % 2 == 1) {
                 // negate boolean
-                v = v.negate();
+                v = v.negateBoolean();
             }
             ctx.setVariable(variable, v);
             return;
diff --git a/src/rockstar/statement/IncrementStatement.java b/src/rockstar/statement/IncrementStatement.java
index 1ddaead..1c8b3a8 100644
--- a/src/rockstar/statement/IncrementStatement.java
+++ b/src/rockstar/statement/IncrementStatement.java
@@ -58,7 +58,7 @@ public void execute(BlockContext ctx) {
             v = v.asBoolean();
             if (count % 2 == 1) {
                 // negate boolean
-                v = v.negate();
+                v = v.negateBoolean();
             }
             ctx.setVariable(variable, v);
             return;