diff --git a/tests/extmod/vfs_posix.py b/tests/extmod/vfs_posix.py
index ebbd08a4a6..bc4c7c2014 100644
--- a/tests/extmod/vfs_posix.py
+++ b/tests/extmod/vfs_posix.py
@@ -88,6 +88,9 @@ print(os.listdir(temp_dir))
 
 # construct new VfsPosix with path argument
 vfs = os.VfsPosix(temp_dir)
+# when VfsPosix is used the intended way via os.mount(), it can only be called
+# with relative paths when the CWD is inside or at its root, so simulate that
+os.chdir(temp_dir)
 print(list(i[0] for i in vfs.ilistdir(".")))
 
 # stat, statvfs (statvfs may not exist)
@@ -112,6 +115,9 @@ vfs.remove("/subdir/micropy_test_dir/test2")
 vfs.rmdir("/subdir/micropy_test_dir")
 vfs.rmdir("/subdir")
 
+# done with vfs, restore CWD
+os.chdir(curdir)
+
 # remove
 os.remove(temp_dir + "/test2")
 print(os.listdir(temp_dir))
diff --git a/tests/extmod/vfs_posix_ilistdir_del.py b/tests/extmod/vfs_posix_ilistdir_del.py
index edb50dfd62..8c8e6978b6 100644
--- a/tests/extmod/vfs_posix_ilistdir_del.py
+++ b/tests/extmod/vfs_posix_ilistdir_del.py
@@ -11,7 +11,13 @@ except (ImportError, AttributeError):
 
 
 def test(testdir):
+    curdir = os.getcwd()
     vfs = os.VfsPosix(testdir)
+    # When VfsPosix is used the intended way via os.mount(), it can only be called
+    # with relative paths when the CWD is inside or at its root, so simulate that.
+    # (Although perhaps calling with a relative path was an oversight in this case
+    # and the respective line below was meant to read `vfs.rmdir("/" + dname)`.)
+    os.chdir(testdir)
     vfs.mkdir("/test_d1")
     vfs.mkdir("/test_d2")
     vfs.mkdir("/test_d3")
@@ -48,6 +54,9 @@ def test(testdir):
         vfs.open("/test", "w").close()
         vfs.remove("/test")
 
+    # Done with vfs, restore CWD.
+    os.chdir(curdir)
+
 
 # We need an empty directory for testing.
 # Skip the test if it already exists.
diff --git a/tests/extmod/vfs_posix_ilistdir_filter.py b/tests/extmod/vfs_posix_ilistdir_filter.py
index c32d124971..5401274605 100644
--- a/tests/extmod/vfs_posix_ilistdir_filter.py
+++ b/tests/extmod/vfs_posix_ilistdir_filter.py
@@ -10,7 +10,11 @@ except (ImportError, AttributeError):
 
 
 def test(testdir):
+    curdir = os.getcwd()
     vfs = os.VfsPosix(testdir)
+    # When VfsPosix is used the intended way via os.mount(), it can only be called
+    # with relative paths when the CWD is inside or at its root, so simulate that.
+    os.chdir(testdir)
 
     dirs = [".a", "..a", "...a", "a.b", "a..b"]
 
@@ -24,6 +28,9 @@ def test(testdir):
 
     print(dirs)
 
+    # Done with vfs, restore CWD.
+    os.chdir(curdir)
+
 
 # We need an empty directory for testing.
 # Skip the test if it already exists.