diff --git a/CMakeLists.txt b/CMakeLists.txt
index c908963b031e4d29addc44b5eb3003e178ab61d7..3f6262143db4fa60426ed9be8845311f46c22dd6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2,7 +2,7 @@ PROJECT(Corpus2Library)
 
 set(corpus2_ver_major "1")
 set(corpus2_ver_minor "0")
-set(corpus2_ver_patch "12")
+set(corpus2_ver_patch "13")
 
 cmake_minimum_required(VERSION 2.8.0)
 
diff --git a/libcorpus2/tagset.cpp b/libcorpus2/tagset.cpp
index 5869159ff0de3113969f1473b0d73e2b20ccaf2d..ab4781696318cbdb397cf9b20f5b946c5f6a66ce 100644
--- a/libcorpus2/tagset.cpp
+++ b/libcorpus2/tagset.cpp
@@ -557,12 +557,20 @@ std::vector<Tag> Tagset::split_tag(const Tag& tag) const
 				if ((v & vm).any()) {
 					if (dup) {
 						for (size_t i = 0; i < sz; ++i) {
-							tags.push_back(tags[i]);
+							Tag new_tag = tags[i];
+							mask_t new_vals = new_tag.get_values();
+							new_vals &= ~ma; // clear whole attr
+							new_vals ^= vm; // add just the new value
+							// tags[i].add_values(vm);
+							new_tag.set_values(new_vals);
+							tags.push_back(new_tag);
 						}
 					}
-					dup = true;
-					for (size_t i = 0; i < sz; ++i) {
-						tags[i].add_values(vm);
+					else {
+						dup = true;
+						for (size_t i = 0; i < sz; ++i) {
+							tags[i].add_values(vm);
+						}
 					}
 				}
 			}