diff --git a/src/cc/firaja/generators/AbstractGenerator.java b/src/cc/firaja/generators/AbstractGenerator.java
index 1ba58e6..ecf4f8f 100644
--- a/src/cc/firaja/generators/AbstractGenerator.java
+++ b/src/cc/firaja/generators/AbstractGenerator.java
@@ -58,13 +58,18 @@ public AbstractGenerator(final int limit)
 	 * is re-initialized to this state.
 	 *
 	 * @param copy the generator to be copied.
+	 * @throws IllegalArgumentException if parameter copy is null
 	 */
 	public AbstractGenerator(final AbstractGenerator<T> copy)
 	{
+		if (copy == null)
+		{
+			throw new IllegalArgumentException("Argument cannot be null");
+		}
 		this.hasLimit = copy.hasLimit;
 		this.limit = copy.limit;
 		this.cursor = copy.cursor;
-
+		this.result = copy.result;
 		storeOriginals();
 	}
 
diff --git a/testsrc/cc/firaja/generators/SequentialNumericalAbstractGenerator.java b/testsrc/cc/firaja/generators/SequentialNumericalAbstractGenerator.java
index 79e8481..ad5a358 100644
--- a/testsrc/cc/firaja/generators/SequentialNumericalAbstractGenerator.java
+++ b/testsrc/cc/firaja/generators/SequentialNumericalAbstractGenerator.java
@@ -205,4 +205,52 @@ public void testNegativeLimitInResize()
 		// THEN
 	}
 
+	@Test
+	public void testConstructorCopy()
+	{
+		// GIVEN
+		Generator<Integer> newGenerator;
+
+		sequentialNumericalAbstractGenerator.next();
+		sequentialNumericalAbstractGenerator.next();
+		sequentialNumericalAbstractGenerator.next();
+		int lastResult = sequentialNumericalAbstractGenerator.last();
+
+
+		// WHEN
+		newGenerator = new AbstractGenerator<Integer>(sequentialNumericalAbstractGenerator)
+		{
+			@Override
+			public Integer generate()
+			{
+				return c();
+			}
+		};
+		int nextResult = sequentialNumericalAbstractGenerator.next();
+
+		// THEN
+		assertEquals(lastResult, (int) newGenerator.last());
+		assertEquals(nextResult, (int) newGenerator.next());
+	}
+
+	@Test(expected = IllegalArgumentException.class)
+	public void testConstructorNullCopy()
+	{
+		// GIVEN
+
+
+		// WHEN
+		new AbstractGenerator<Object>(null)
+		{
+			@Override
+			public Object generate()
+			{
+				return null;
+			}
+		};
+
+		// THEN
+
+	}
+
 }