diff --git a/extmod/vfs_posix.c b/extmod/vfs_posix.c
index d63bb5be7bff4..e29b47cccda83 100644
--- a/extmod/vfs_posix.c
+++ b/extmod/vfs_posix.c
@@ -46,6 +46,9 @@
 #ifdef _MSC_VER
 #include <direct.h> // For mkdir etc.
 #endif
+#ifdef _WIN32
+#include <windows.h>
+#endif
 
 typedef struct _mp_obj_vfs_posix_t {
     mp_obj_base_t base;
@@ -55,21 +58,23 @@ typedef struct _mp_obj_vfs_posix_t {
 } mp_obj_vfs_posix_t;
 
 STATIC const char *vfs_posix_get_path_str(mp_obj_vfs_posix_t *self, mp_obj_t path) {
-    if (self->root_len == 0) {
-        return mp_obj_str_get_str(path);
+    const char *path_str = mp_obj_str_get_str(path);
+    if (self->root_len == 0 || path_str[0] != '/') {
+        return path_str;
     } else {
-        self->root.len = self->root_len;
-        vstr_add_str(&self->root, mp_obj_str_get_str(path));
+        self->root.len = self->root_len - 1;
+        vstr_add_str(&self->root, path_str);
         return vstr_null_terminated_str(&self->root);
     }
 }
 
 STATIC mp_obj_t vfs_posix_get_path_obj(mp_obj_vfs_posix_t *self, mp_obj_t path) {
-    if (self->root_len == 0) {
+    const char *path_str = mp_obj_str_get_str(path);
+    if (self->root_len == 0 || path_str[0] != '/') {
         return path;
     } else {
-        self->root.len = self->root_len;
-        vstr_add_str(&self->root, mp_obj_str_get_str(path));
+        self->root.len = self->root_len - 1;
+        vstr_add_str(&self->root, path_str);
         return mp_obj_new_str(self->root.buf, self->root.len);
     }
 }
@@ -107,7 +112,28 @@ STATIC mp_obj_t vfs_posix_make_new(const mp_obj_type_t *type, size_t n_args, siz
     mp_obj_vfs_posix_t *vfs = mp_obj_malloc(mp_obj_vfs_posix_t, type);
     vstr_init(&vfs->root, 0);
     if (n_args == 1) {
-        vstr_add_str(&vfs->root, mp_obj_str_get_str(args[0]));
+        const char *root = mp_obj_str_get_str(args[0]);
+        // if the root is relative, make it absolute, otherwise we'll get confused by chdir
+        #ifdef _WIN32
+        char buf[MICROPY_ALLOC_PATH_MAX + 1];
+        DWORD result = GetFullPathNameA(root, sizeof(buf), buf, NULL);
+        if (result > 0 && result < sizeof(buf)) {
+            vstr_add_str(&vfs->root, buf);
+        } else {
+            mp_raise_OSError(GetLastError());
+        }
+        #else
+        if (root[0] != '\0' && root[0] != '/') {
+            char buf[MICROPY_ALLOC_PATH_MAX + 1];
+            const char *cwd = getcwd(buf, sizeof(buf));
+            if (cwd == NULL) {
+                mp_raise_OSError(errno);
+            }
+            vstr_add_str(&vfs->root, cwd);
+            vstr_add_char(&vfs->root, '/');
+        }
+        vstr_add_str(&vfs->root, root);
+        #endif
         vstr_add_char(&vfs->root, '/');
     }
     vfs->root_len = vfs->root.len;
@@ -160,7 +186,14 @@ STATIC mp_obj_t vfs_posix_getcwd(mp_obj_t self_in) {
     if (ret == NULL) {
         mp_raise_OSError(errno);
     }
-    ret += self->root_len;
+    if (self->root_len > 0) {
+        ret += self->root_len - 1;
+        #ifdef _WIN32
+        if (*ret == '\\') {
+            *(char *)ret = '/';
+        }
+        #endif
+    }
     return mp_obj_new_str(ret, strlen(ret));
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(vfs_posix_getcwd_obj, vfs_posix_getcwd);
diff --git a/tests/extmod/vfs_posix.py b/tests/extmod/vfs_posix.py
index 05dc0f537e3ca..bc4c7c2014b6c 100644
--- a/tests/extmod/vfs_posix.py
+++ b/tests/extmod/vfs_posix.py
@@ -88,6 +88,9 @@ def write_files_without_closing():
 
 # 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)
@@ -99,6 +102,22 @@ def write_files_without_closing():
 print(type(list(vfs.ilistdir("."))[0][0]))
 print(type(list(vfs.ilistdir(b"."))[0][0]))
 
+# chdir should not affect absolute paths (regression test)
+vfs.mkdir("/subdir")
+vfs.mkdir("/subdir/micropy_test_dir")
+with vfs.open("/subdir/micropy_test_dir/test2", "w") as f:
+    f.write("wrong")
+vfs.chdir("/subdir")
+with vfs.open("/test2", "r") as f:
+    print(f.read())
+os.chdir(curdir)
+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.py.exp b/tests/extmod/vfs_posix.py.exp
index 99922e621d4c2..bd1ec7bad67b2 100644
--- a/tests/extmod/vfs_posix.py.exp
+++ b/tests/extmod/vfs_posix.py.exp
@@ -10,6 +10,7 @@ next_file_no <= base_file_no True
 <class 'tuple'>
 <class 'str'>
 <class 'bytes'>
+hello
 []
 remove OSError
 False
diff --git a/tests/extmod/vfs_posix_enoent.py b/tests/extmod/vfs_posix_enoent.py
new file mode 100644
index 0000000000000..e6010d79d58f0
--- /dev/null
+++ b/tests/extmod/vfs_posix_enoent.py
@@ -0,0 +1,42 @@
+# Test for VfsPosix error conditions
+
+try:
+    import os
+    import sys
+
+    os.VfsPosix
+except (ImportError, AttributeError):
+    print("SKIP")
+    raise SystemExit
+
+if sys.platform == "win32":
+    # Windows doesn't let you delete the current directory, so this cannot be
+    # tested.
+    print("SKIP")
+    raise SystemExit
+
+# We need an empty directory for testing.
+# Skip the test if it already exists.
+temp_dir = "vfs_posix_enoent_test_dir"
+try:
+    os.stat(temp_dir)
+    print("SKIP")
+    raise SystemExit
+except OSError:
+    pass
+
+curdir = os.getcwd()
+os.mkdir(temp_dir)
+os.chdir(temp_dir)
+os.rmdir(curdir + "/" + temp_dir)
+try:
+    print("getcwd():", os.getcwd())
+except OSError as e:
+    # expecting ENOENT = 2
+    print("getcwd():", repr(e))
+
+try:
+    print("VfsPosix():", os.VfsPosix("something"))
+except OSError as e:
+    # expecting ENOENT = 2
+    print("VfsPosix():", repr(e))
diff --git a/tests/extmod/vfs_posix_enoent.py.exp b/tests/extmod/vfs_posix_enoent.py.exp
new file mode 100644
index 0000000000000..f2d9a0d551068
--- /dev/null
+++ b/tests/extmod/vfs_posix_enoent.py.exp
@@ -0,0 +1,2 @@
+getcwd(): OSError(2,)
+VfsPosix(): OSError(2,)
diff --git a/tests/extmod/vfs_posix_ilistdir_del.py b/tests/extmod/vfs_posix_ilistdir_del.py
index edb50dfd6229c..8c8e6978b6540 100644
--- a/tests/extmod/vfs_posix_ilistdir_del.py
+++ b/tests/extmod/vfs_posix_ilistdir_del.py
@@ -11,7 +11,13 @@
 
 
 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 c32d1249710de..54012746057a8 100644
--- a/tests/extmod/vfs_posix_ilistdir_filter.py
+++ b/tests/extmod/vfs_posix_ilistdir_filter.py
@@ -10,7 +10,11 @@
 
 
 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.
diff --git a/tests/extmod/vfs_posix_paths.py b/tests/extmod/vfs_posix_paths.py
new file mode 100644
index 0000000000000..5806a34521a23
--- /dev/null
+++ b/tests/extmod/vfs_posix_paths.py
@@ -0,0 +1,92 @@
+# Test for VfsPosix with relative paths
+
+try:
+    import os
+
+    os.VfsPosix
+except (ImportError, AttributeError):
+    print("SKIP")
+    raise SystemExit
+
+# We need a directory for testing that doesn't already exist.
+# Skip the test if it does exist.
+temp_dir = "vfs_posix_paths_test_dir"
+try:
+    import os
+
+    os.stat(temp_dir)
+    print("SKIP")
+    raise SystemExit
+except OSError:
+    pass
+
+curdir = os.getcwd()
+os.mkdir(temp_dir)
+
+# construct new VfsPosix with absolute path argument
+temp_dir_abs = os.getcwd() + os.sep + temp_dir
+vfs = os.VfsPosix(temp_dir_abs)
+# 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_abs)
+vfs.mkdir("subdir")
+vfs.mkdir("subdir/one")
+print('listdir("/"):', sorted(i[0] for i in vfs.ilistdir("/")))
+print('listdir("."):', sorted(i[0] for i in vfs.ilistdir(".")))
+print('getcwd() in {"", "/"}:', vfs.getcwd() in {"", "/"})
+print('chdir("subdir"):', vfs.chdir("subdir"))
+print("getcwd():", vfs.getcwd())
+print('mkdir("two"):', vfs.mkdir("two"))
+f = vfs.open("file.py", "w")
+f.write("print('hello')")
+f.close()
+print('listdir("/"):', sorted(i[0] for i in vfs.ilistdir("/")))
+print('listdir("/subdir"):', sorted(i[0] for i in vfs.ilistdir("/subdir")))
+print('listdir("."):', sorted(i[0] for i in vfs.ilistdir(".")))
+try:
+    f = vfs.open("/subdir/file.py", "r")
+    print(f.read())
+    f.close()
+except Exception as e:
+    print(e)
+import sys
+
+sys.path.insert(0, "")
+try:
+    import file
+
+    print(file)
+except Exception as e:
+    print(e)
+del sys.path[0]
+vfs.remove("file.py")
+vfs.rmdir("two")
+vfs.rmdir("/subdir/one")
+vfs.chdir("/")
+vfs.rmdir("/subdir")
+
+# done with vfs, restore CWD
+os.chdir(curdir)
+
+# some integration tests with a mounted VFS
+os.mount(os.VfsPosix(temp_dir_abs), "/mnt")
+os.mkdir("/mnt/dir")
+print('chdir("/mnt/dir"):', os.chdir("/mnt/dir"))
+print("getcwd():", os.getcwd())
+print('chdir("/mnt"):', os.chdir("/mnt"))
+print("getcwd():", os.getcwd())
+print('chdir("/"):', os.chdir("/"))
+print("getcwd():", os.getcwd())
+print('chdir("/mnt/dir"):', os.chdir("/mnt/dir"))
+print("getcwd():", os.getcwd())
+print('chdir(".."):', os.chdir(".."))
+print("getcwd():", os.getcwd())
+os.rmdir("/mnt/dir")
+os.umount("/mnt")
+
+# restore CWD
+os.chdir(curdir)
+
+# rmdir
+os.rmdir(temp_dir)
+print(temp_dir in os.listdir())
diff --git a/tests/extmod/vfs_posix_paths.py.exp b/tests/extmod/vfs_posix_paths.py.exp
new file mode 100644
index 0000000000000..ecc13222aaaeb
--- /dev/null
+++ b/tests/extmod/vfs_posix_paths.py.exp
@@ -0,0 +1,23 @@
+listdir("/"): ['subdir']
+listdir("."): ['subdir']
+getcwd() in {"", "/"}: True
+chdir("subdir"): None
+getcwd(): /subdir
+mkdir("two"): None
+listdir("/"): ['subdir']
+listdir("/subdir"): ['file.py', 'one', 'two']
+listdir("."): ['file.py', 'one', 'two']
+print('hello')
+hello
+<module 'file' from 'file.py'>
+chdir("/mnt/dir"): None
+getcwd(): /mnt/dir
+chdir("/mnt"): None
+getcwd(): /mnt
+chdir("/"): None
+getcwd(): /
+chdir("/mnt/dir"): None
+getcwd(): /mnt/dir
+chdir(".."): None
+getcwd(): /mnt
+False