diff --git a/fsspec/conftest.py b/fsspec/conftest.py
index 393e4c465..47b49c939 100644
--- a/fsspec/conftest.py
+++ b/fsspec/conftest.py
@@ -17,7 +17,7 @@ def m():
     """
     m = fsspec.filesystem("memory")
     m.store.clear()
-    m.pseudo_dirs.clear()
+    m.pseudo_dirs = [""]
     try:
         yield m
     finally:
diff --git a/fsspec/implementations/memory.py b/fsspec/implementations/memory.py
index 334f9db26..9356a56eb 100644
--- a/fsspec/implementations/memory.py
+++ b/fsspec/implementations/memory.py
@@ -116,6 +116,9 @@ def makedirs(self, path, exist_ok=False):
 
     def rmdir(self, path):
         path = self._strip_protocol(path)
+        if path == "":
+            # silently avoid deleting FS root
+            return
         if path in self.pseudo_dirs:
             if not self.ls(path):
                 self.pseudo_dirs.remove(path)
@@ -124,7 +127,7 @@ def rmdir(self, path):
         else:
             raise FileNotFoundError(path)
 
-    def exists(self, path):
+    def exists(self, path, **kwargs):
         path = self._strip_protocol(path)
         return path in self.store or path in self.pseudo_dirs
 
diff --git a/fsspec/implementations/tests/test_memory.py b/fsspec/implementations/tests/test_memory.py
index 184c9eeda..c647fac9e 100644
--- a/fsspec/implementations/tests/test_memory.py
+++ b/fsspec/implementations/tests/test_memory.py
@@ -150,3 +150,9 @@ def test_seekable(m):
     f.seek(1)
     assert f.read(1) == "a"
     assert f.tell() == 2
+
+
+def test_remove_all(m):
+    m.touch("afile")
+    m.rm("/", recursive=True)
+    assert not m.ls("/")