diff --git a/src/descriptors.rs b/src/descriptors.rs
index 288a209921..036fd88ab7 100644
--- a/src/descriptors.rs
+++ b/src/descriptors.rs
@@ -175,6 +175,8 @@ impl Descriptors {
                 output: Cell::new(None),
                 type_: StreamType::File(File {
                     fd: preopen.descriptor,
+                    descriptor_type: crate::bindings::filesystem::get_type(preopen.descriptor)
+                        .trapping_unwrap(),
                     position: Cell::new(0),
                     append: false,
                 }),
@@ -332,6 +334,8 @@ impl Descriptors {
     }
 
     pub fn get_dir(&self, fd: Fd) -> Result<&File, Errno> {
+        // FIXME: do we look at the StreamType::File(File { descriptor_type }) and make sure it
+        // really is a DescriptorType::Directory here?
         self.get_file_with_error(fd, wasi::ERRNO_NOTDIR)
     }
 
diff --git a/src/lib.rs b/src/lib.rs
index 630227bb76..be2448e9cb 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1313,11 +1313,13 @@ pub unsafe extern "C" fn path_open(
         let mut ds = state.descriptors_mut();
         let file = ds.get_dir(fd)?;
         let result = filesystem::open_at(file.fd, at_flags, path, o_flags, flags, mode)?;
+        let descriptor_type = filesystem::get_type(result)?;
         let desc = Descriptor::Streams(Streams {
             input: Cell::new(None),
             output: Cell::new(None),
             type_: StreamType::File(File {
                 fd: result,
+                descriptor_type,
                 position: Cell::new(0),
                 append,
             }),
@@ -2000,6 +2002,9 @@ pub struct File {
     /// The handle to the preview2 descriptor that this file is referencing.
     fd: filesystem::Descriptor,
 
+    /// The descriptor type, as supplied by filesystem::get_type at opening
+    descriptor_type: filesystem::DescriptorType,
+
     /// The current-position pointer.
     position: Cell<filesystem::Filesize>,