diff --git a/api/snapshot.go b/api/snapshot.go
index a9061eb1..3256242d 100644
--- a/api/snapshot.go
+++ b/api/snapshot.go
@@ -209,24 +209,37 @@ func apiSnapshotsCreate(c *gin.Context) {
 			}
 		}
 
-		list := deb.NewPackageList()
-
-		// verify package refs and build package list using fresh factory
-		for _, ref := range b.PackageRefs {
-			p, err := taskPackageCollection.ByKey([]byte(ref))
-			if err != nil {
-				if err == database.ErrNotFound {
-					return &task.ProcessReturnValue{Code: http.StatusNotFound, Value: nil}, fmt.Errorf("package %s: %s", ref, err)
-				}
-				return &task.ProcessReturnValue{Code: http.StatusInternalServerError, Value: nil}, err
-			}
-			err = list.Add(p)
-			if err != nil {
-				return &task.ProcessReturnValue{Code: http.StatusBadRequest, Value: nil}, err
+		// Merge packages from all source snapshots
+		var refList *deb.PackageRefList
+		if len(freshSources) > 0 {
+			refList = freshSources[0].RefList()
+			for i := 1; i < len(freshSources); i++ {
+				refList = refList.Merge(freshSources[i].RefList(), true, false)
 			}
+		} else {
+			refList = deb.NewPackageRefList()
 		}
 
-		snapshot = deb.NewSnapshotFromRefList(b.Name, freshSources, deb.NewPackageRefListFromPackageList(list), b.Description)
+		// Add any explicitly specified package refs on top
+		if len(b.PackageRefs) > 0 {
+			list := deb.NewPackageList()
+			for _, ref := range b.PackageRefs {
+				p, err := taskPackageCollection.ByKey([]byte(ref))
+				if err != nil {
+					if err == database.ErrNotFound {
+						return &task.ProcessReturnValue{Code: http.StatusNotFound, Value: nil}, fmt.Errorf("package %s: %s", ref, err)
+					}
+					return &task.ProcessReturnValue{Code: http.StatusInternalServerError, Value: nil}, err
+				}
+				err = list.Add(p)
+				if err != nil {
+					return &task.ProcessReturnValue{Code: http.StatusBadRequest, Value: nil}, err
+				}
+			}
+			refList = refList.Merge(deb.NewPackageRefListFromPackageList(list), true, false)
+		}
+
+		snapshot = deb.NewSnapshotFromRefList(b.Name, freshSources, refList, b.Description)
 
 		err = taskSnapshotCollection.Add(snapshot)
 		if err != nil {
diff --git a/system/t12_api/publish.py b/system/t12_api/publish.py
index a9d5cf0d..cd92f775 100644
--- a/system/t12_api/publish.py
+++ b/system/t12_api/publish.py
@@ -1207,11 +1207,10 @@ class PublishSwitchAPITestSnapshot(APITest):
         self.check_equal(all_repos.status_code, 200)
         self.check_in(repo_expected, all_repos.json())
 
-        # FIXME: what should exist here ? publish snapshot of snapshot
         self.check_not_exists(
             "public/" + prefix + "/pool/main/b/boost-defaults/libboost-program-options-dev_1.49.0.1_i386.deb")
-        self.check_not_exists("public/" + prefix +
-                              "/pool/main/p/pyspi/pyspi-0.6.1-1.3.stripped.dsc")
+        self.check_exists("public/" + prefix +
+                          "/pool/main/p/pyspi/pyspi-0.6.1-1.3.stripped.dsc")
 
         task = self.delete_task("/api/publish/" + prefix + "/wheezy")
         self.check_task(task)