diff --git a/spacy/tokens/doc.pyx b/spacy/tokens/doc.pyx
index 50b19d4c1..55a83913b 100644
--- a/spacy/tokens/doc.pyx
+++ b/spacy/tokens/doc.pyx
@@ -447,9 +447,8 @@ cdef class Doc:
 
         cdef Span span = self[start:end]
         # Get LexemeC for newly merged token
-        new_orth = ''.join([t.string for t in span])
-        if span[-1].whitespace_:
-            new_orth = new_orth[:-1]
+        new_orth = ''.join([t.text_with_ws for t in span])
+        new_orth = new_orth[:-len(span[-1].whitespace_)]
         cdef const LexemeC* lex = self.vocab.get(self.mem, new_orth)
         # House the new merged token where it starts
         cdef TokenC* token = &self.data[start]
@@ -508,16 +507,26 @@ cdef int set_children_from_heads(TokenC* tokens, int length) except -1:
     cdef TokenC* head
     cdef TokenC* child
     cdef int i
+    # Set number of left/right children to 0. We'll increment it in the loops.
+    for i in range(length):
+        tokens[i].l_kids = 0
+        tokens[i].r_kids = 0
+        tokens[i].l_edge = i
+        tokens[i].r_edge = i
     # Set left edges
     for i in range(length):
         child = &tokens[i]
         head = &tokens[i + child.head]
-        if child < head and child.l_edge < head.l_edge:
-            head.l_edge = child.l_edge
+        if child < head:
+            if child.l_edge < head.l_edge:
+                head.l_edge = child.l_edge
+            head.l_kids += 1
+        
     # Set right edges --- same as above, but iterate in reverse
     for i in range(length-1, -1, -1):
         child = &tokens[i]
         head = &tokens[i + child.head]
-        if child > head and child.r_edge > head.r_edge:
-            head.r_edge = child.r_edge
-
+        if child > head:
+            if child.r_edge > head.r_edge:
+                head.r_edge = child.r_edge
+            head.r_kids += 1
diff --git a/tests/tokens/test_tokens_api.py b/tests/tokens/test_tokens_api.py
index 675f00235..b40513b02 100644
--- a/tests/tokens/test_tokens_api.py
+++ b/tests/tokens/test_tokens_api.py
@@ -109,3 +109,30 @@ def test_set_ents(EN):
     assert ent.label_ == 'PRODUCT'
     assert ent.start == 2
     assert ent.end == 4
+
+
+def test_merge(EN):
+    doc = EN('WKRO played songs by the beach boys all night')
+
+    assert len(doc) == 9
+    # merge 'The Beach Boys'
+    doc.merge(doc[4].idx, doc[6].idx + len(doc[6]), 'NAMED', 'LEMMA', 'TYPE')
+    assert len(doc) == 7
+
+    assert doc[4].text == 'the beach boys'
+    assert doc[4].text_with_ws == 'the beach boys '
+    assert doc[4].tag_ == 'NAMED'
+
+
+@pytest.mark.models
+def test_merge_children(EN):
+    """Test that attachments work correctly after merging."""
+    doc = EN('WKRO played songs by the beach boys all night')
+    # merge 'The Beach Boys'
+    doc.merge(doc[4].idx, doc[6].idx + len(doc[6]), 'NAMED', 'LEMMA', 'TYPE')
+    
+    for word in doc:
+        if word.i < word.head.i:
+            assert word in list(word.head.lefts)
+        elif word.i > word.head.i:
+            assert word in list(word.head.rights)