diff --git a/stdlib/3/pathlib.pyi b/stdlib/3/pathlib.pyi
index 7871efa04..b470d1f0d 100644
--- a/stdlib/3/pathlib.pyi
+++ b/stdlib/3/pathlib.pyi
@@ -77,6 +77,8 @@ class Path(PurePath):
     def group(self) -> str: ...
     def is_dir(self) -> bool: ...
     def is_file(self) -> bool: ...
+    if sys.version_info >= (3, 7):
+        def is_mount(self) -> bool: ...
     def is_symlink(self) -> bool: ...
     def is_socket(self) -> bool: ...
     def is_fifo(self) -> bool: ...
diff --git a/third_party/2/pathlib2.pyi b/third_party/2/pathlib2.pyi
index 7871efa04..b470d1f0d 100644
--- a/third_party/2/pathlib2.pyi
+++ b/third_party/2/pathlib2.pyi
@@ -77,6 +77,8 @@ class Path(PurePath):
     def group(self) -> str: ...
     def is_dir(self) -> bool: ...
     def is_file(self) -> bool: ...
+    if sys.version_info >= (3, 7):
+        def is_mount(self) -> bool: ...
     def is_symlink(self) -> bool: ...
     def is_socket(self) -> bool: ...
     def is_fifo(self) -> bool: ...