diff --git a/litebox/src/fs/errors.rs b/litebox/src/fs/errors.rs
index 459caaea27..ae5ba04c46 100644
--- a/litebox/src/fs/errors.rs
+++ b/litebox/src/fs/errors.rs
@@ -79,6 +79,8 @@ pub enum SeekError {
     InvalidOffset,
     #[error("non-seekable file")]
     NonSeekable,
+    #[error("file descriptor is not open for seeking")]
+    NotOpenForSeeking,
     #[error("I/O error")]
     Io,
 }
@@ -92,6 +94,8 @@ pub enum TruncateError {
     IsDirectory,
     #[error("file is not opened for writing")]
     NotForWriting,
+    #[error("file descriptor is not open for writing")]
+    NotOpenForWriting,
     #[error("file descriptor points to a terminal device")]
     IsTerminalDevice,
     #[error("I/O error")]
@@ -194,6 +198,8 @@ pub enum ReadDirError {
     ClosedFd,
     #[error("fd does not point to a directory")]
     NotADirectory,
+    #[error("file descriptor is not open for reading")]
+    NotOpenForReading,
     #[error("I/O error")]
     Io,
 }
diff --git a/litebox/src/fs/resolver.rs b/litebox/src/fs/resolver.rs
index 225f440261..6ea5bacd84 100644
--- a/litebox/src/fs/resolver.rs
+++ b/litebox/src/fs/resolver.rs
@@ -651,6 +651,9 @@ impl<Platform: sync::RawSyncPrimitivesProvider, Backend: super::backend::Backend
             .entry_handle(fd)
             .ok_or(ReadError::ClosedFd)?;
         let mut entry = entry.get_entry_mut();
+        if entry.entry.path_only {
+            return Err(ReadError::NotForReading);
+        }
         // XXX(jayb): This over-holds the descriptor-entry lock across backend I/O. We need a
         // smaller per-open-file-description primitive for position/append serialization, so the
         // descriptor entry can be unlocked before potentially blocking backend calls.
@@ -662,10 +665,6 @@ impl<Platform: sync::RawSyncPrimitivesProvider, Backend: super::backend::Backend
         if !entry.entry.read_allowed {
             return Err(ReadError::NotForReading);
         }
-        if entry.entry.path_only {
-            // TODO(jayb): Add an error variant for operations not permitted on O_PATH fds.
-            unimplemented!("read from O_PATH fd")
-        }
 
         let read_offset = match seek_behavior {
             SeekBehavior::NonSeekable | SeekBehavior::ZeroPosition => 0,
@@ -699,6 +698,9 @@ impl<Platform: sync::RawSyncPrimitivesProvider, Backend: super::backend::Backend
             .entry_handle(fd)
             .ok_or(WriteError::ClosedFd)?;
         let mut entry = entry.get_entry_mut();
+        if entry.entry.path_only {
+            return Err(WriteError::NotForWriting);
+        }
         // XXX(jayb): This over-holds the descriptor-entry lock across backend I/O. We need a
         // smaller per-open-file-description primitive for position/append serialization, so the
         // descriptor entry can be unlocked before potentially blocking backend calls.
@@ -710,10 +712,6 @@ impl<Platform: sync::RawSyncPrimitivesProvider, Backend: super::backend::Backend
         if !entry.entry.write_allowed {
             return Err(WriteError::NotForWriting);
         }
-        if entry.entry.path_only {
-            // TODO(jayb): Add an error variant for operations not permitted on O_PATH fds.
-            unimplemented!("write to O_PATH fd")
-        }
 
         let write_offset = match seek_behavior {
             SeekBehavior::NonSeekable | SeekBehavior::ZeroPosition => 0,
@@ -752,8 +750,7 @@ impl<Platform: sync::RawSyncPrimitivesProvider, Backend: super::backend::Backend
             Handle::Dir(_) => return Err(SeekError::NotAFile),
         };
         if entry.entry.path_only {
-            // TODO(jayb): Add an error variant for operations not permitted on O_PATH fds.
-            unimplemented!("seek on O_PATH fd")
+            return Err(SeekError::NotOpenForSeeking);
         }
 
         match entry.entry.seek_behavior {
@@ -806,13 +803,12 @@ impl<Platform: sync::RawSyncPrimitivesProvider, Backend: super::backend::Backend
             Handle::File(file) => file,
             Handle::Dir(_) => return Err(TruncateError::IsDirectory),
         };
+        if entry.entry.path_only {
+            return Err(TruncateError::NotOpenForWriting);
+        }
         if !entry.entry.write_allowed {
             return Err(TruncateError::NotForWriting);
         }
-        if entry.entry.path_only {
-            // TODO(jayb): Add an error variant for operations not permitted on O_PATH fds.
-            unimplemented!("truncate O_PATH fd")
-        }
 
         self.backend.truncate(file, length)?;
         if reset_offset {
@@ -957,8 +953,7 @@ impl<Platform: sync::RawSyncPrimitivesProvider, Backend: super::backend::Backend
             .ok_or(ReadDirError::ClosedFd)?;
         let entry = entry.get_entry();
         if entry.entry.path_only {
-            // TODO(jayb): Add an error variant for operations not permitted on O_PATH fds.
-            unimplemented!("read_dir on O_PATH fd")
+            return Err(ReadDirError::NotOpenForReading);
         }
         let dir = match &entry.entry.handle {
             Handle::File(_) => return Err(ReadDirError::NotADirectory),
diff --git a/litebox_common_linux/src/errno/mod.rs b/litebox_common_linux/src/errno/mod.rs
index c5397ab4c2..6107f83b6e 100644
--- a/litebox_common_linux/src/errno/mod.rs
+++ b/litebox_common_linux/src/errno/mod.rs
@@ -213,6 +213,7 @@ impl From<litebox::fs::errors::SeekError> for Errno {
             }
             litebox::fs::errors::SeekError::InvalidOffset => Errno::EINVAL,
             litebox::fs::errors::SeekError::NonSeekable => Errno::ESPIPE,
+            litebox::fs::errors::SeekError::NotOpenForSeeking => Errno::EBADF,
             litebox::fs::errors::SeekError::Io => Errno::EIO,
             _ => unimplemented!(),
         }
@@ -540,6 +541,7 @@ impl From<litebox::fs::errors::ReadDirError> for Errno {
     fn from(value: litebox::fs::errors::ReadDirError) -> Self {
         match value {
             litebox::fs::errors::ReadDirError::NotADirectory => Errno::ENOTDIR,
+            litebox::fs::errors::ReadDirError::NotOpenForReading => Errno::EBADF,
             _ => unimplemented!(),
         }
     }
@@ -601,6 +603,7 @@ impl From<litebox::fs::errors::TruncateError> for Errno {
         match value {
             litebox::fs::errors::TruncateError::IsDirectory => Errno::EISDIR,
             litebox::fs::errors::TruncateError::NotForWriting => Errno::EACCES,
+            litebox::fs::errors::TruncateError::NotOpenForWriting => Errno::EBADF,
             litebox::fs::errors::TruncateError::IsTerminalDevice => Errno::EINVAL,
             litebox::fs::errors::TruncateError::ClosedFd => Errno::EBADF,
             litebox::fs::errors::TruncateError::Io => Errno::EIO,