diff --git a/src/nox_poetry/sessions.py b/src/nox_poetry/sessions.py
index 7214cc1e..7bcc6cfb 100644
--- a/src/nox_poetry/sessions.py
+++ b/src/nox_poetry/sessions.py
@@ -98,7 +98,7 @@ def install(self, *args: str, **kwargs: Any) -> None:
         args_extras = [_split_extras(arg) for arg in args]
 
         if "." in [arg for arg, _ in args_extras]:
-            package = self.build_package(distribution_format=DistributionFormat.WHEEL)
+            package = self.build_package()
 
             def rewrite(arg: str, extras: Optional[str]) -> str:
                 if arg != ".":
@@ -120,7 +120,7 @@ def rewrite(arg: str, extras: Optional[str]) -> str:
     def installroot(
         self,
         *,
-        distribution_format: str,
+        distribution_format: str = DistributionFormat.WHEEL,
         extras: Iterable[str] = (),
     ) -> None:
         """Install the root package into a Nox session using Poetry.
@@ -184,7 +184,9 @@ def export_requirements(self) -> Path:
 
         return path
 
-    def build_package(self, *, distribution_format: str) -> str:
+    def build_package(
+        self, *, distribution_format: str = DistributionFormat.WHEEL
+    ) -> str:
         """Build a distribution archive for the package.
 
         This function uses `poetry build`_ to build a wheel or sdist archive for
diff --git a/src/nox_poetry/sessions.pyi b/src/nox_poetry/sessions.pyi
index e0f187a3..c05fb848 100644
--- a/src/nox_poetry/sessions.pyi
+++ b/src/nox_poetry/sessions.pyi
@@ -21,10 +21,10 @@ Python = Optional[Union[str, Sequence[str], bool]]
 class _PoetrySession:
     def install(self, *args: str, **kwargs: Any) -> None: ...
     def installroot(
-        self, *, distribution_format: str, extras: Iterable[str] = ...
+        self, *, distribution_format: str = ..., extras: Iterable[str] = ...
     ) -> None: ...
     def export_requirements(self) -> Path: ...
-    def build_package(self, *, distribution_format: str) -> str: ...
+    def build_package(self, *, distribution_format: str = ...) -> str: ...
 
 class Session:
     poetry: _PoetrySession