diff --git a/spacy/tokens/spans.pyx b/spacy/tokens/spans.pyx
index c39f8976c..99efad4b9 100644
--- a/spacy/tokens/spans.pyx
+++ b/spacy/tokens/spans.pyx
@@ -16,9 +16,13 @@ cdef class Span:
     def __cinit__(self, Doc tokens, int start, int end, int label=0, vector=None,
                   vector_norm=None):
         if start < 0:
-            start = tokens.length - start
+            start = tokens.length + start
+        start = min(tokens.length, max(0, start))
+
         if end < 0:
-            end = tokens.length - end
+            end = tokens.length + end
+        end = min(tokens.length, max(start, end))
+
         self.doc = tokens
         self.start = start
         self.end = end
diff --git a/tests/tokens/test_tokens_api.py b/tests/tokens/test_tokens_api.py
index fc1b52143..a272a8e3b 100644
--- a/tests/tokens/test_tokens_api.py
+++ b/tests/tokens/test_tokens_api.py
@@ -12,17 +12,51 @@ def test_getitem(EN):
     with pytest.raises(IndexError):
         tokens[len(tokens)]
 
+    def to_str(span):
+       return '/'.join(token.orth_ for token in span)
+
     span = tokens[1:1]
-    assert not '/'.join(token.orth_ for token in span)
+    assert not to_str(span)
     span = tokens[1:4]
-    assert '/'.join(token.orth_ for token in span) == 'it/back/!'
+    assert to_str(span) == 'it/back/!'
     span = tokens[1:4:1]
-    assert '/'.join(token.orth_ for token in span) == 'it/back/!'
+    assert to_str(span) == 'it/back/!'
     with pytest.raises(ValueError):
         tokens[1:4:2]
     with pytest.raises(ValueError):
         tokens[1:4:-1]
 
+    span = tokens[-3:6]
+    assert to_str(span) == 'He/pleaded'
+    span = tokens[4:-1]
+    assert to_str(span) == 'He/pleaded'
+    span = tokens[-5:-3]
+    assert to_str(span) == 'back/!'
+    span = tokens[5:4]
+    assert span.start == span.end == 5 and not to_str(span)
+    span = tokens[4:-3]
+    assert span.start == span.end == 4 and not to_str(span)
+
+    span = tokens[:]
+    assert to_str(span) == 'Give/it/back/!/He/pleaded/.'
+    span = tokens[4:]
+    assert to_str(span) == 'He/pleaded/.'
+    span = tokens[:4]
+    assert to_str(span) == 'Give/it/back/!'
+    span = tokens[:-3]
+    assert to_str(span) == 'Give/it/back/!'
+    span = tokens[-3:]
+    assert to_str(span) == 'He/pleaded/.'
+
+    span = tokens[4:50]
+    assert to_str(span) == 'He/pleaded/.'
+    span = tokens[-50:4]
+    assert to_str(span) == 'Give/it/back/!'
+    span = tokens[-50:-40]
+    assert span.start == span.end == 0 and not to_str(span)
+    span = tokens[40:50]
+    assert span.start == span.end == 7 and not to_str(span)
+
 
 @pytest.mark.models
 def test_serialize(EN):