diff --git a/deb/reflist.go b/deb/reflist.go
index 25cb0b6e1..30396548c 100644
--- a/deb/reflist.go
+++ b/deb/reflist.go
@@ -196,31 +196,21 @@ func (l *PackageRefList) Diff(r *PackageRefList, packageCollection *PackageColle
 
 	// until we reached end of both lists
 	for il < ll || ir < lr {
-		// if we've exhausted left list, pull the rest from the right
-		if il == ll {
-			pr, err = packageCollection.ByKey(r.Refs[ir])
-			if err != nil {
-				return nil, err
-			}
-			result = append(result, PackageDiff{Left: nil, Right: pr})
-			ir++
-			continue
+		var rl, rr []byte
+		if il < ll {
+			rl = l.Refs[il]
 		}
-		// if we've exhausted right list, pull the rest from the left
-		if ir == lr {
-			pl, err = packageCollection.ByKey(l.Refs[il])
-			if err != nil {
-				return nil, err
-			}
-			result = append(result, PackageDiff{Left: pl, Right: nil})
-			il++
-			continue
+		if ir < lr {
+			rr = r.Refs[ir]
 		}
 
-		// refs on both sides are present, load them
-		rl, rr := l.Refs[il], r.Refs[ir]
 		// compare refs
 		rel := bytes.Compare(rl, rr)
+		// an unset ref is less than all others, but since it represents the end
+		// of a reflist, it should be *greater*, so flip the comparison result
+		if rl == nil || rr == nil {
+			rel = -rel
+		}
 
 		if rel == 0 {
 			// refs are identical, so are packages, advance pointer
@@ -229,14 +219,14 @@ func (l *PackageRefList) Diff(r *PackageRefList, packageCollection *PackageColle
 			pl, pr = nil, nil
 		} else {
 			// load pl & pr if they haven't been loaded before
-			if pl == nil {
+			if pl == nil && rl != nil {
 				pl, err = packageCollection.ByKey(rl)
 				if err != nil {
 					return nil, err
 				}
 			}
 
-			if pr == nil {
+			if pr == nil && rr != nil {
 				pr, err = packageCollection.ByKey(rr)
 				if err != nil {
 					return nil, err
diff --git a/deb/reflist_test.go b/deb/reflist_test.go
index d0ce21f5e..ec7ed09f7 100644
--- a/deb/reflist_test.go
+++ b/deb/reflist_test.go
@@ -237,6 +237,41 @@ func (s *PackageRefListSuite) TestDiff(c *C) {
 
 }
 
+func (s *PackageRefListSuite) TestDiffCompactsAtEnd(c *C) {
+	db, _ := goleveldb.NewOpenDB(c.MkDir())
+	coll := NewPackageCollection(db)
+
+	packages := []*Package{
+		{Name: "app", Version: "1.1~bp1", Architecture: "i386"},  //0
+		{Name: "app", Version: "1.1~bp2", Architecture: "i386"},  //1
+		{Name: "app", Version: "1.1~bp2", Architecture: "amd64"}, //2
+	}
+
+	for _, p := range packages {
+		coll.Update(p)
+	}
+
+	listA := NewPackageList()
+	listA.Add(packages[0])
+
+	listB := NewPackageList()
+	listB.Add(packages[1])
+	listB.Add(packages[2])
+
+	reflistA := NewPackageRefListFromPackageList(listA)
+	reflistB := NewPackageRefListFromPackageList(listB)
+
+	diffAB, err := reflistA.Diff(reflistB, coll)
+	c.Check(err, IsNil)
+	c.Check(diffAB, HasLen, 2)
+
+	c.Check(diffAB[0].Left, IsNil)
+	c.Check(diffAB[0].Right.String(), Equals, "app_1.1~bp2_amd64")
+
+	c.Check(diffAB[1].Left.String(), Equals, "app_1.1~bp1_i386")
+	c.Check(diffAB[1].Right.String(), Equals, "app_1.1~bp2_i386")
+}
+
 func (s *PackageRefListSuite) TestMerge(c *C) {
 	db, _ := goleveldb.NewOpenDB(c.MkDir())
 	coll := NewPackageCollection(db)