diff --git a/src/file.rs b/src/file.rs
index 5d310ed..9e16f26 100644
--- a/src/file.rs
+++ b/src/file.rs
@@ -55,6 +55,10 @@ impl std::ops::DerefMut for File {
 impl File {
     #[allow(clippy::doc_markdown)]
     /// Open a netCDF file in read only mode.
+    ///
+    /// Consider using [`crate::open`] instead to open with
+    /// a generic `Path` object, and ensure read-only on
+    /// the `File`
     pub fn open(path: &path::Path) -> error::Result<Self> {
         let f = CString::new(path.to_str().unwrap()).unwrap();
         let mut ncid: nc_type = -1;
@@ -126,6 +130,37 @@ impl File {
     }
 }
 
+/// File that does not allow writing to it, enforced by
+/// borrow rules (can not get `mut File`)
+///
+/// `Deref`s to `File`, but does not provide mutable access,
+/// so the following code will not compile:
+/// ```compile_fail
+/// # fn main() -> netcdf::Result<()>{
+/// let file = netcdf::open("file.nc")?;
+/// file.add_dimension("somedim", 10)?;
+/// # }
+/// ```
+#[derive(Debug)]
+pub struct ReadOnlyFile {
+    file: File,
+}
+
+impl std::ops::Deref for ReadOnlyFile {
+    type Target = File;
+    fn deref(&self) -> &Self::Target {
+        &self.file
+    }
+}
+
+impl ReadOnlyFile {
+    pub(crate) fn open(path: &path::Path) -> error::Result<Self> {
+        Ok(Self {
+            file: File::open(path)?
+        })
+    }
+}
+
 #[cfg(feature = "memory")]
 /// The memory mapped file is kept in this structure to keep the
 /// lifetime of the buffer longer than the file.
diff --git a/src/lib.rs b/src/lib.rs
index 932e301..d0b1cb2 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -100,11 +100,11 @@ where
 }
 
 /// Open a netcdf file in read mode
-pub fn open<P>(name: P) -> error::Result<File>
+pub fn open<P>(name: P) -> error::Result<ReadOnlyFile>
 where
     P: AsRef<std::path::Path>,
 {
-    File::open(name.as_ref())
+    ReadOnlyFile::open(name.as_ref())
 }
 
 #[cfg(feature = "memory")]
diff --git a/tests/lib.rs b/tests/lib.rs
index 4a03295..7e974c8 100644
--- a/tests/lib.rs
+++ b/tests/lib.rs
@@ -1591,8 +1591,8 @@ fn set_get_endian() {
         {
             // re-open it
             // and get "some variable" endian_value
-            let mut file_o = netcdf::open(&f).unwrap();
-            let var = &mut file_o.root_mut().variable("some_variable").unwrap();
+            let file_o = netcdf::open(&f).unwrap();
+            let var = &file_o.variable("some_variable").unwrap();
             assert_eq!(var.endian_value(), Ok(*i));
             // close it (done when `file_a` goes out of scope)
         }