diff --git a/mypy/fastparse2.py b/mypy/fastparse2.py
index 6b2f8d562156..1f8ffda457ea 100644
--- a/mypy/fastparse2.py
+++ b/mypy/fastparse2.py
@@ -148,6 +148,7 @@ def __init__(self,
         self.options = options
         self.is_stub = is_stub
         self.errors = errors
+        self.unicode_literals = False
 
     def fail(self, msg: str, line: int, column: int) -> None:
         self.errors.report(line, column, msg)
@@ -653,6 +654,8 @@ def visit_ImportFrom(self, n: ast27.ImportFrom) -> ImportBase:
                            n.level,
                            [(a.name, a.asname) for a in n.names])
         self.imports.append(i)
+        if n.module == '__future__' and any(nm.name == 'unicode_literals' for nm in n.names):
+            self.unicode_literals = True
         return i
 
     # Global(identifier* names)
@@ -880,6 +883,8 @@ def visit_Str(self, s: ast27.Str) -> Expression:
             contents = str(n)[2:-1]
             return StrExpr(contents)
         else:
+            if self.unicode_literals and all(ord(c) < 128 for c in s.s):  # ASCII only
+                return StrExpr(s.s)
             return UnicodeExpr(s.s)
 
     # Ellipsis
diff --git a/test-data/unit/python2eval.test b/test-data/unit/python2eval.test
index b750de8b12a1..df94be932d13 100644
--- a/test-data/unit/python2eval.test
+++ b/test-data/unit/python2eval.test
@@ -151,15 +151,39 @@ f(**params)
 [out]
 
 [case testFromFutureImportUnicodeLiterals2_python2]
+# coding=utf-8
 from __future__ import unicode_literals
 def f(x): # type: (str) -> None
   pass
 f(b'')
-f(u'')
-f('')
+f(u'щось')
+f('щось інше')
 [out]
-_program.py:5: error: Argument 1 to "f" has incompatible type "unicode"; expected "str"
 _program.py:6: error: Argument 1 to "f" has incompatible type "unicode"; expected "str"
+_program.py:7: error: Argument 1 to "f" has incompatible type "unicode"; expected "str"
+
+[case testUnicodeLiteralsFutureImportAllASCII_python2]
+# coding=utf-8
+from __future__ import unicode_literals
+x = None  # type: str
+x = 'не латиниця'  # Error
+x = 'only ascii'  # This is however OK
+reveal_type('another ascii')
+[out]
+_program.py:4: error: Incompatible types in assignment (expression has type "unicode", variable has type "str")
+_program.py:6: error: Revealed type is 'builtins.str'
+
+[case testUnicodeLiteralsFutureImportAllASCIIvariant1_python2]
+from __future__ import absolute_import, unicode_literals
+x = None  # type: str
+x = 'only ascii'
+[out]
+
+[case testUnicodeLiteralsFutureImportAllASCIIvariant2_python2]
+from __future__ import unicode_literals as something_else
+x = None  # type: str
+x = 'only ascii'
+[out]
 
 [case testStrUnicodeCompatibility_python2]
 import typing