diff --git a/httprest/api.py b/httprest/api.py
index 5990c82..302e926 100644
--- a/httprest/api.py
+++ b/httprest/api.py
@@ -1,5 +1,6 @@
 """API."""
 
+import urllib.parse
 from typing import Optional as _Optional
 from typing import Union as _Union
 
@@ -31,7 +32,7 @@ def __init__(
     def _request(
         self,
         method: str,
-        endpoint: str,
+        endpoint: _Optional[str] = None,
         data: _Optional[_Union[dict, bytes]] = None,
         json: _Optional[dict] = None,
         headers: _Optional[dict] = None,
@@ -42,7 +43,7 @@ def _request(
         # pylint: disable=too-many-arguments
         """Make API request.
 
-        :param endpoint: API endpoint. Will be appended to the base URL
+        :param endpoint: API endpoint. Will be joined with the base URL
 
         Other parameters are the same as for the `HTTPClient.request` method
         """
@@ -57,8 +58,8 @@ def _request(
             cert=cert,
         )
 
-    def _build_url(self, endpoint: str) -> str:
-        return f"{self._base_url}/{endpoint.strip('/')}"
+    def _build_url(self, endpoint: _Optional[str]) -> str:
+        return urllib.parse.urljoin(self._base_url, endpoint)
 
     def __str__(self) -> str:
         return f"{self.__class__.__name__}(base_url='{self._base_url}')"
diff --git a/tests/unit/fakes.py b/tests/unit/fakes.py
index 95a4057..d3668d1 100644
--- a/tests/unit/fakes.py
+++ b/tests/unit/fakes.py
@@ -4,16 +4,19 @@
 from typing import Optional
 
 from httprest import API
+from httprest.http import HTTPResponse
 from httprest.http.fake_client import FakeHTTPClient
 
 
 class _TestAPI(API):
     """API client for tests."""
 
-    def make_call(self):
+    def make_call(
+        self, endpoint: Optional[str] = "/example/endpoint/"
+    ) -> HTTPResponse:
         """Make API call."""
         return self._request(
-            "POST", "/example/endpoint/", json={"k": "v"}, headers={"h": "v"}
+            "POST", endpoint, json={"k": "v"}, headers={"h": "v"}
         )
 
 
diff --git a/tests/unit/test_api.py b/tests/unit/test_api.py
index 7dbfe40..c0f4146 100644
--- a/tests/unit/test_api.py
+++ b/tests/unit/test_api.py
@@ -1,5 +1,9 @@
 """Tests for the API client."""
 
+import typing
+
+import pytest
+
 from httprest.http import HTTPResponse
 
 from .fakes import FakeHTTPClient, build_api
@@ -19,6 +23,21 @@ def test_api_call():
             "headers": {"h": "v"},
             "json": {"k": "v"},
             "method": "POST",
-            "url": "http://fake.com/example/endpoint",
+            "url": "http://fake.com/example/endpoint/",
         },
     ]
+
+
+@pytest.mark.parametrize("endpoint", ["", None])
+def test_url_without_endpoint(endpoint: typing.Optional[str]):
+    """Test for request URL when endpoint is not specified.
+
+    The base URL must be used.
+    """
+    base = "http://fake.com"
+    comps = build_api(
+        base_url=base,
+        http_client=FakeHTTPClient(responses=[HTTPResponse(200, b"", {})]),
+    )
+    comps.api.make_call(endpoint=endpoint)
+    assert comps.http_client.history[0]["url"] == base