diff --git a/BUILD b/BUILD
index 97e3f45ba4..ee31cd86b7 100644
--- a/BUILD
+++ b/BUILD
@@ -512,6 +512,7 @@ internal_copied_filegroup(
 py_proto_library(
     name = "protobuf_python",
     srcs = WELL_KNOWN_PROTOS,
+    srcs_version = "PY2AND3",
     include = "src",
     protoc = ":protoc",
     py_extra_srcs = [":python_srcs"],
@@ -555,6 +556,7 @@ py_proto_library(
 py_library(
     name = "python_tests",
     srcs = [":python_test_srcs"],
+    srcs_version = "PY2AND3",
     deps = [
         ":protobuf_python",
         ":python_common_test_protos",
diff --git a/six.BUILD b/six.BUILD
index 55c53a4231..fb0b3604cd 100644
--- a/six.BUILD
+++ b/six.BUILD
@@ -8,5 +8,6 @@ genrule(
 py_library(
   name = "six",
   srcs = ["six.py"],
+  srcs_version = "PY2AND3",
   visibility = ["//visibility:public"],
 )