diff --git a/ethereumj-core/src/main/java/org/ethereum/vm/DataWord.java b/ethereumj-core/src/main/java/org/ethereum/vm/DataWord.java
index c06eab38..517caa12 100644
--- a/ethereumj-core/src/main/java/org/ethereum/vm/DataWord.java
+++ b/ethereumj-core/src/main/java/org/ethereum/vm/DataWord.java
@@ -151,6 +151,11 @@ public class DataWord implements Comparable<DataWord> {
             if (this.data[i] != 0) break;
         }
     }
+    
+    public void bnot() {
+        if (this.isZero()) return;
+        this.data = ByteUtil.copyToArray(MAX_VALUE.subtract(this.value()));
+    }
 
     // By	: Holger
     // From	: http://stackoverflow.com/a/24023466/459349
diff --git a/ethereumj-core/src/main/java/org/ethereum/vm/OpCode.java b/ethereumj-core/src/main/java/org/ethereum/vm/OpCode.java
index e4aae830..b3203e04 100644
--- a/ethereumj-core/src/main/java/org/ethereum/vm/OpCode.java
+++ b/ethereumj-core/src/main/java/org/ethereum/vm/OpCode.java
@@ -32,7 +32,7 @@ public enum OpCode {
 	/** (0x08) Exponential operation			*/
 	EXP(0x08,	2),
 	/** (0x09) Negation operation				*/
-	NEG(0x09,	1),
+	BNOT(0x09,	1),
 	/** (0x0a) Less-than comparison				*/
 	LT(0X0a,	2),
 	/** (0x0b) Greater-than comparison			*/
diff --git a/ethereumj-core/src/main/java/org/ethereum/vm/VM.java b/ethereumj-core/src/main/java/org/ethereum/vm/VM.java
index 966acfe4..baf8d634 100644
--- a/ethereumj-core/src/main/java/org/ethereum/vm/VM.java
+++ b/ethereumj-core/src/main/java/org/ethereum/vm/VM.java
@@ -282,9 +282,9 @@ public class VM {
                     program.stackPush(word1);
                     program.step();
                 }	break;
-                case NEG:{
+                case BNOT:{
                 	DataWord word1 = program.stackPop();
-                    word1.negate();
+                    word1.bnot();
 
                     if (logger.isInfoEnabled())
                         hint = "" + word1.value();
diff --git a/ethereumj-core/src/test/java/org/ethereum/vm/VMTest.java b/ethereumj-core/src/test/java/org/ethereum/vm/VMTest.java
index 4893b3a3..b28a5e1e 100644
--- a/ethereumj-core/src/test/java/org/ethereum/vm/VMTest.java
+++ b/ethereumj-core/src/test/java/org/ethereum/vm/VMTest.java
@@ -998,12 +998,12 @@ public class VMTest {
         }
     }
 
-    @Test  // NEG OP
-    public void testNEG_1() {
+    @Test  // BNOT OP
+    public void testBNOT_1() {
 
         VM vm = new VM();
         program =  new Program(Hex.decode("600109"), invoke);
-        String expected = "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF";
+        String expected = "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFE";
 
         vm.step(program);
         vm.step(program);
@@ -1011,12 +1011,12 @@ public class VMTest {
         assertEquals(expected, Hex.toHexString(program.stack.peek().getData()).toUpperCase());
     }
 
-    @Test  // NEG OP
-    public void testNEG_2() {
+    @Test  // BNOT OP
+    public void testBNOT_2() {
 
         VM vm = new VM();
         program =  new Program(Hex.decode("61A00309"), invoke);
-        String expected = "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5FFD";
+        String expected = "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5FFC";
 
         vm.step(program);
         vm.step(program);
@@ -1024,8 +1024,8 @@ public class VMTest {
         assertEquals(expected, Hex.toHexString(program.stack.peek().getData()).toUpperCase());
     }
 
-    @Test  // NEG OP
-    public void testNEG_3() {
+    @Test  // BNOT OP
+    public void testBNOT_3() {
 
         VM vm = new VM();
         program =  new Program(Hex.decode("61000009"), invoke);
@@ -1037,8 +1037,8 @@ public class VMTest {
         assertEquals(expected, Hex.toHexString(program.stack.peek().getData()).toUpperCase());
     }
 
-    @Test(expected=StackTooSmallException.class)  // NEG OP
-    public void testNEG_4() {
+    @Test(expected=StackTooSmallException.class)  // BNOT OP
+    public void testBNOT_4() {
 
         VM vm = new VM();
         program =  new Program(Hex.decode("09"), invoke);