diff --git a/arraycontainer.go b/arraycontainer.go
index ddac9257..db80fb91 100644
--- a/arraycontainer.go
+++ b/arraycontainer.go
@@ -514,7 +514,7 @@ func (ac *arrayContainer) iandNot(a container) container {
 }
 
 func (ac *arrayContainer) iandNotRun16(rc *runContainer16) container {
-	//p("arrayContainer.iandNotRun16() starting")
+	//p("arrayContainer.iandNotRun16() starting; rc = %s", rc)
 
 	rcb := rc.toBitmapContainer()
 	//p("rcb has size %v", rcb.getCardinality())
@@ -522,19 +522,10 @@ func (ac *arrayContainer) iandNotRun16(rc *runContainer16) container {
 	acb := ac.toBitmapContainer()
 	//p("acb has size %v", acb.getCardinality())
 
-	anew := acb.andNotBitmap(rcb)
-	//p("anew has size %v", anew.getCardinality())
+	acb.iandNotBitmapSurely(rcb)
+	//p("after iandNotBit, acb has size %v", acb.getCardinality())
 
-	switch x := anew.(type) {
-	case *arrayContainer:
-		*ac = *x
-	case *bitmapContainer:
-		*ac = *(x.toArrayContainer())
-	case *runContainer16:
-		*ac = *(x.toArrayContainer())
-	default:
-		panic("unsupported container type")
-	}
+	*ac = *(acb.toArrayContainer())
 	return ac
 }
 
diff --git a/bitmapcontainer.go b/bitmapcontainer.go
index a845ae17..d32fb70a 100644
--- a/bitmapcontainer.go
+++ b/bitmapcontainer.go
@@ -585,13 +585,13 @@ func (bc *bitmapContainer) andNotRun16(rc *runContainer16) container {
 }
 
 func (bc *bitmapContainer) iandNot(a container) container {
-	p("bitmapContainer.iandNot() starting")
+	//p("bitmapContainer.iandNot() starting")
 
 	switch x := a.(type) {
 	case *arrayContainer:
 		return bc.iandNotArray(x)
 	case *bitmapContainer:
-		return bc.iandNotBitmap(x)
+		return bc.iandNotBitmapSurely(x)
 	case *runContainer16:
 		return bc.iandNotRun16(x)
 	}
@@ -649,7 +649,10 @@ func (bc *bitmapContainer) iandNotBitmapSurely(value2 *bitmapContainer) *bitmapC
 	return bc
 }
 
-func (bc *bitmapContainer) iandNotBitmap(value2 *bitmapContainer) container {
+// warning, this function may not actually modify the bc array in place!
+// TODO: delete? Mostly replaced with iandNotBitmapSurely
+/*
+func (bc *bitmapContainer) iandNotBitmapSCARY(value2 *bitmapContainer) container {
 	newCardinality := int(popcntMaskSlice(bc.bitmap, value2.bitmap))
 	if newCardinality > arrayDefaultMaxSize {
 		for k := 0; k < len(bc.bitmap); k++ {
@@ -662,6 +665,7 @@ func (bc *bitmapContainer) iandNotBitmap(value2 *bitmapContainer) container {
 	fillArrayANDNOT(ac.content, bc.bitmap, value2.bitmap)
 	return ac
 }
+*/
 
 func (bc *bitmapContainer) contains(i uint16) bool { //testbit
 	x := int(i)
diff --git a/example_roaring_test.go b/example_roaring_test.go
index 3861c99c..6efeb1ed 100644
--- a/example_roaring_test.go
+++ b/example_roaring_test.go
@@ -112,11 +112,13 @@ func TestExample2_roaring061(t *testing.T) {
 	for i := uint32(0); i < 10000; i += 3 {
 		rb1.Add(i)
 	}
-	fmt.Printf("\nrb1card before doing AndNot(rb3): %v\n",
-		rb1.GetCardinality())
+	fmt.Printf("\n rb1card before doing AndNot(rb3): %v, rb3card=%v\n",
+		rb1.GetCardinality(), rb3.GetCardinality())
 	rb1.AndNot(rb3)
 	rb1card := rb1.GetCardinality()
 	if rb1card != 1 {
+		//rb1.RunOptimize()
+		//fmt.Printf("\n rb1 = %s\n", rb1)
 		t.Errorf("Only the value 0 should survive the andNot; rb1card = %v", rb1card)
 	}
 }
diff --git a/rlei.go b/rlei.go
index 01b122de..11c9253e 100644
--- a/rlei.go
+++ b/rlei.go
@@ -545,10 +545,12 @@ func (rc *runContainer16) andNotBitmap(bc *bitmapContainer) container {
 }
 
 func (rc *runContainer16) toBitmapContainer() *bitmapContainer {
+	p("run16 toBitmap starting; rc has %v ranges", len(rc.iv))
 	bc := newBitmapContainer()
 	for i := range rc.iv {
-		bc.iaddRange(int(rc.iv[i].start), int(rc.iv[i].last+1))
+		bc.iaddRange(int(rc.iv[i].start), int(rc.iv[i].last)+1)
 	}
+	bc.computeCardinality()
 	return bc
 }
 
diff --git a/roaring.go b/roaring.go
index 66a0c535..5ab5d105 100644
--- a/roaring.go
+++ b/roaring.go
@@ -1005,7 +1005,7 @@ func (rb *Bitmap) AddRange(rangeStart, rangeEnd uint64) {
 		i := rb.highlowcontainer.getIndex(hb)
 
 		if i >= 0 {
-			c := rb.highlowcontainer.getWritableContainerAtIndex(i).iaddRange(int(containerStart), int(containerLast+1))
+			c := rb.highlowcontainer.getWritableContainerAtIndex(i).iaddRange(int(containerStart), int(containerLast)+1)
 			rb.highlowcontainer.setContainerAtIndex(i, c)
 		} else { // *think* the range of ones must never be
 			// empty.