diff --git a/src/shims/files.rs b/src/shims/files.rs
index 0deecbfb0a..394211107c 100644
--- a/src/shims/files.rs
+++ b/src/shims/files.rs
@@ -301,8 +301,7 @@ impl FileDescription for FileHandle {
     }
 
     fn read<'tcx>(
-        &self,
-        _self_ref: &FileDescriptionRef,
+        self: FileDescriptionRef<Self>,
         communicate_allowed: bool,
         ptr: Pointer,
         len: usize,
@@ -319,8 +318,7 @@ impl FileDescription for FileHandle {
     }
 
     fn write<'tcx>(
-        &self,
-        _self_ref: &FileDescriptionRef,
+        self: FileDescriptionRef<Self>,
         communicate_allowed: bool,
         ptr: Pointer,
         len: usize,
@@ -346,7 +344,7 @@ impl FileDescription for FileHandle {
     }
 
     fn close<'tcx>(
-        self: Box<Self>,
+        self,
         communicate_allowed: bool,
         _ecx: &mut MiriInterpCx<'tcx>,
     ) -> InterpResult<'tcx, io::Result<()>> {
@@ -357,7 +355,7 @@ impl FileDescription for FileHandle {
             // to handle possible errors correctly.
             let result = self.file.sync_all();
             // Now we actually close the file and return the result.
-            drop(*self);
+            drop(self);
             interp_ok(result)
         } else {
             // We drop the file, this closes it but ignores any errors
@@ -366,7 +364,7 @@ impl FileDescription for FileHandle {
             // `/dev/urandom` which are read-only. Check
             // https://github.com/rust-lang/miri/issues/999#issuecomment-568920439
             // for a deeper discussion.
-            drop(*self);
+            drop(self);
             interp_ok(Ok(()))
         }
     }
diff --git a/src/shims/unix/fs.rs b/src/shims/unix/fs.rs
index db53e40fba..5da9f95ce0 100644
--- a/src/shims/unix/fs.rs
+++ b/src/shims/unix/fs.rs
@@ -13,7 +13,7 @@ use rustc_data_structures::fx::FxHashMap;
 
 use self::shims::time::system_time_to_duration;
 use crate::helpers::check_min_vararg_count;
-use crate::shims::files::{EvalContextExt as _, FileHandle, FileDescription, FileDescriptionRef};
+use crate::shims::files::{EvalContextExt as _, FileHandle};
 use crate::shims::os_str::bytes_to_os_str;
 use crate::shims::unix::fd::{FlockOp, UnixFileDescription};
 use crate::*;
diff --git a/src/shims/windows/foreign_items.rs b/src/shims/windows/foreign_items.rs
index 588109e92c..72d76fef67 100644
--- a/src/shims/windows/foreign_items.rs
+++ b/src/shims/windows/foreign_items.rs
@@ -250,7 +250,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                     creation_disposition,
                     flags_and_attributes,
                     template_file,
-                ] = this.check_shim(abi, ExternAbi::System { unwind: false }, link_name, args)?;
+                ] = this.check_shim(abi, sys_conv, link_name, args)?;
                 let handle = this.CreateFileW(
                     file_name,
                     desired_access,
@@ -263,8 +263,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 this.write_scalar(handle.to_scalar(this), dest)?;
             }
             "GetFileInformationByHandle" => {
-                let [handle, info] =
-                    this.check_shim(abi, ExternAbi::System { unwind: false }, link_name, args)?;
+                let [handle, info] = this.check_shim(abi, sys_conv, link_name, args)?;
                 let res = this.GetFileInformationByHandle(handle, info)?;
                 this.write_scalar(res, dest)?;
             }
diff --git a/src/shims/windows/fs.rs b/src/shims/windows/fs.rs
index 0b0ff34e5e..13ed4d5475 100644
--- a/src/shims/windows/fs.rs
+++ b/src/shims/windows/fs.rs
@@ -1,6 +1,5 @@
 use std::fs::{Metadata, OpenOptions};
 use std::io;
-use std::io::ErrorKind;
 use std::path::PathBuf;
 use std::time::SystemTime;
 
@@ -25,7 +24,7 @@ impl FileDescription for DirHandle {
     }
 
     fn close<'tcx>(
-        self: Box<Self>,
+        self,
         _communicate_allowed: bool,
         _ecx: &mut MiriInterpCx<'tcx>,
     ) -> InterpResult<'tcx, io::Result<()>> {
@@ -51,7 +50,7 @@ impl FileDescription for MetadataHandle {
     }
 
     fn close<'tcx>(
-        self: Box<Self>,
+        self,
         _communicate_allowed: bool,
         _ecx: &mut MiriInterpCx<'tcx>,
     ) -> InterpResult<'tcx, io::Result<()>> {
@@ -115,7 +114,7 @@ impl FileAttributes {
     fn new<'tcx>(
         mut value: u32,
         ecx: &mut MiriInterpCx<'tcx>,
-    ) -> InterpResult<'tcx, Result<FileAttributes, IoError>> {
+    ) -> InterpResult<'tcx, FileAttributes> {
         let file_attribute_normal = ecx.eval_windows_u32("c", "FILE_ATTRIBUTE_NORMAL");
         let file_flag_backup_semantics = ecx.eval_windows_u32("c", "FILE_FLAG_BACKUP_SEMANTICS");
         let file_flag_open_reparse_point =
@@ -128,7 +127,7 @@ impl FileAttributes {
         } else if value & file_flag_open_reparse_point != 0 {
             value &= !file_flag_open_reparse_point;
             out |= FileAttributes::OPEN_REPARSE;
-        } else if value & file_attribute_normal {
+        } else if value & file_attribute_normal != 0 {
             value &= !file_attribute_normal;
             out |= FileAttributes::NORMAL;
         }
@@ -140,7 +139,7 @@ impl FileAttributes {
         if out == FileAttributes::ZERO {
             out = FileAttributes::NORMAL;
         }
-        interp_ok(Ok(out))
+        interp_ok(out)
     }
 }
 
@@ -189,7 +188,8 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
             throw_unsup_format!("CreateFileW: Security attributes are not supported");
         }
 
-        if attributes & FileAttributes::OPEN_REPARSE != 0 && creation_disposition == CreateAlways {
+        if attributes.contains(FileAttributes::OPEN_REPARSE) && creation_disposition == CreateAlways
+        {
             throw_machine_stop!(TerminationInfo::Abort("Invalid CreateFileW argument combination: FILE_FLAG_OPEN_REPARSE_POINT with CREATE_ALWAYS".to_string()));
         }
 
diff --git a/src/shims/windows/handle.rs b/src/shims/windows/handle.rs
index e47478533e..917a3a7a46 100644
--- a/src/shims/windows/handle.rs
+++ b/src/shims/windows/handle.rs
@@ -233,7 +233,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
             }
             Handle::File(fd_num) =>
                 if let Some(fd) = this.machine.fds.remove(fd_num) {
-                    let err = fd.close(this.machine.communicate(), this)?;
+                    let err = fd.close_ref(this.machine.communicate(), this)?;
                     if let Err(e) = err {
                         this.set_last_error(e)?;
                         this.eval_windows("c", "FALSE")