diff --git a/jedi/api/completion.py b/jedi/api/completion.py
index 332cab0f..f5f81df0 100644
--- a/jedi/api/completion.py
+++ b/jedi/api/completion.py
@@ -457,6 +457,8 @@ def _extract_string_while_in_string(leaf, position):
         if leaf.line == position[0]:
             kwargs['endpos'] = position[1] - leaf.column
         match = _string_start.match(leaf.value, **kwargs)
+        if not match:
+            return None, None, None
         start = match.group(0)
         if leaf.line == position[0] and position[1] < leaf.column + match.end():
             return None, None, None
diff --git a/test/test_api/test_completion.py b/test/test_api/test_completion.py
index fed496ab..cc10db72 100644
--- a/test/test_api/test_completion.py
+++ b/test/test_api/test_completion.py
@@ -299,6 +299,9 @@ current_dirname = os.path.basename(dirname(dirname(dirname(__file__))))
         (f2, os_path + 'join(["tes"]', 10, ['t' + s]),
         (f2, os_path + 'join(["tes"])', 10, ['t' + s]),
         (f2, os_path + 'join("test", "test_cac" + x,', 22, ['he.py']),
+
+        # GH #1528
+        (f2, "'a' 'b'", 4, Ellipsis),
     ]
 )
 def test_file_path_completions(Script, file, code, column, expected):
@@ -306,7 +309,7 @@ def test_file_path_completions(Script, file, code, column, expected):
     if isinstance(column, tuple):
         line, column = column
     comps = Script(code, path=file).complete(line=line, column=column)
-    if expected == "A LOT":
+    if expected is Ellipsis:
         assert len(comps) > 100  # This is basically global completions.
     else:
         assert [c.complete for c in comps] == expected