python
diff --git a/‎mypy/checkexpr.py
Lines changed: 1 addition & 1 deletion b/‎mypy/checkexpr.py
Lines changed: 1 addition & 1 deletion
diff --git a/‎mypy/checkstrformat.py
Lines changed: 3 additions & 3 deletions b/‎mypy/checkstrformat.py
Lines changed: 3 additions & 3 deletions
diff --git a/‎mypy/exprtotype.py
Lines changed: 2 additions & 2 deletions b/‎mypy/exprtotype.py
Lines changed: 2 additions & 2 deletions
@@ -861,7 +861,7 @@ def visit_op_expr(self, e: OpExpr) -> Type:
         if e.op == '*' and isinstance(e.left, ListExpr):
             # Expressions of form [...] * e get special type inference.
             return self.check_list_multiply(e)
-        if e.op == '%' and isinstance(e.left, StrExpr):
+        if e.op == '%' and isinstance(e.left, (StrExpr, BytesExpr)):
             return self.strfrm_checker.check_str_interpolation(cast(StrExpr, e.left), e.right)
         left_type = self.accept(e.left)
 
 
@@ -8,7 +8,7 @@
     Type, AnyType, TupleType, Instance, UnionType
 )
 from mypy.nodes import (
-    Node, StrExpr, TupleExpr, DictExpr, Context
+    Node, StrExpr, BytesExpr, TupleExpr, DictExpr, Context
 )
 if False:
     # break import cycle only needed for mypy
@@ -136,7 +136,7 @@ def check_simple_str_interpolation(self, specifiers: List[ConversionSpecifier],
     def check_mapping_str_interpolation(self, specifiers: List[ConversionSpecifier],
                                        replacements: Node) -> None:
         dict_with_only_str_literal_keys = (isinstance(replacements, DictExpr) and
-                                          all(isinstance(k, StrExpr)
+                                          all(isinstance(k, (StrExpr, BytesExpr))
                                               for k, v in cast(DictExpr, replacements).items))
         if dict_with_only_str_literal_keys:
             mapping = {}  # type: Dict[str, Type]
@@ -255,7 +255,7 @@ def check_type(type: Type = None) -> None:
         def check_node(node: Node) -> None:
             """int, or str with length 1"""
             type = self.accept(node, expected_type)
-            if isinstance(node, StrExpr) and len(cast(StrExpr, node).value) != 1:
+            if isinstance(node, (StrExpr, BytesExpr)) and len(cast(StrExpr, node).value) != 1:
                 self.msg.requires_int_or_char(context)
             check_type(type)
 
 
@@ -1,7 +1,7 @@
 """Translate an expression (Node) to a Type value."""
 
 from mypy.nodes import (
-    Node, NameExpr, MemberExpr, IndexExpr, TupleExpr, ListExpr, StrExpr, EllipsisExpr
+    Node, NameExpr, MemberExpr, IndexExpr, TupleExpr, ListExpr, StrExpr, BytesExpr, EllipsisExpr
 )
 from mypy.parsetype import parse_str_as_type, TypeParseError
 from mypy.types import Type, UnboundType, TypeList, EllipsisType
@@ -42,7 +42,7 @@ def expr_to_unanalyzed_type(expr: Node) -> Type:
     elif isinstance(expr, ListExpr):
         return TypeList([expr_to_unanalyzed_type(t) for t in expr.items],
                         line=expr.line)
-    elif isinstance(expr, StrExpr):
+    elif isinstance(expr, (StrExpr, BytesExpr)):
         # Parse string literal type.
         try:
             result = parse_str_as_type(expr.value, expr.line)