diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3ceecee..6a6f4fa 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,7 +4,7 @@
 
 ## 3.1.2
 
-* Verify that base prefix doesn't end with '/'
+* Verify that base prefix starts with '/' but doesn't end with '/'
 * Improve base prefix log message
 * Never send body for HEAD requests (again)
 
diff --git a/radicale/app/__init__.py b/radicale/app/__init__.py
index 685fb77..f1233e0 100644
--- a/radicale/app/__init__.py
+++ b/radicale/app/__init__.py
@@ -191,9 +191,10 @@ class Application(ApplicationPartDelete, ApplicationPartHead,
         base_prefix_src = ("HTTP_X_SCRIPT_NAME" if "HTTP_X_SCRIPT_NAME" in
                            environ else "SCRIPT_NAME")
         base_prefix = environ.get(base_prefix_src, "")
-        if base_prefix.endswith("/"):
-            logger.error("Base prefix (from %s) must not end with '/': %r",
-                         base_prefix_src, base_prefix)
+        if base_prefix and (base_prefix[0] != "/" or base_prefix[-1] == "/"):
+            logger.error("Base prefix (from %s) must %s with '/': %r",
+                         base_prefix_src, "not end" if base_prefix[-1] == "/"
+                         else "start", base_prefix)
             if base_prefix_src == "HTTP_X_SCRIPT_NAME":
                 return response(*httputils.BAD_REQUEST)
             return response(*httputils.INTERNAL_SERVER_ERROR)
diff --git a/radicale/tests/test_base.py b/radicale/tests/test_base.py
index ea01cf6..03e2f63 100644
--- a/radicale/tests/test_base.py
+++ b/radicale/tests/test_base.py
@@ -67,7 +67,8 @@ permissions: RrWw""")
 
     def test_root_broken_script_name(self) -> None:
         """GET request at "/" with SCRIPT_NAME ending with "/"."""
-        self.get("/", check=500, SCRIPT_NAME="/radicale/")
+        for script_name in ["/", "/radicale/", "radicale"]:
+            self.get("/", check=500, SCRIPT_NAME=script_name)
 
     def test_root_http_x_script_name(self) -> None:
         """GET request at "/" with HTTP_X_SCRIPT_NAME."""
@@ -78,7 +79,8 @@ permissions: RrWw""")
 
     def test_root_broken_http_x_script_name(self) -> None:
         """GET request at "/" with HTTP_X_SCRIPT_NAME ending with "/"."""
-        self.get("/", check=400, HTTP_X_SCRIPT_NAME="/radicale/")
+        for script_name in ["/", "/radicale/", "radicale"]:
+            self.get("/", check=400, HTTP_X_SCRIPT_NAME=script_name)
 
     def test_sanitized_path(self) -> None:
         """GET request with unsanitized paths."""