diff --git a/CHANGELOG.md b/CHANGELOG.md
index f779cf7..ec0432d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 Changes in each release are listed below.
 
+## 0.9.1 09-Aug-2021 (Pre-release)
+* Added alternative version of mwalib_metafits_context_new (mwalib_metafits_context_new2) to FFI interface which does not require an MWAVersion and will determine it via the MODE keyword.
+* Fixed errors, ommissions in comment/documentation for FFI function mwalib_metafits_get_expected_volt_filename().
+
 ## 0.9.0 09-Aug-2021 (Pre-release)
 * Added mwa_version <Option<MWAVersion>> to MetafitsContext struct.
 * When working only with a MetafitsContext, a None can be passed in lieu of an MWAVersion, and mwalib will attempt to determine the correct MWAVersion based on the MODE keyword from the metafits file.
diff --git a/Cargo.toml b/Cargo.toml
index e57a99d..fd8d60a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "mwalib"
-version = "0.9.0"
+version = "0.9.1"
 homepage = "https://github.com/MWATelescope/mwalib"
 repository = "https://github.com/MWATelescope/mwalib"
 readme = "README.md"
diff --git a/examples/mwalib-print-context.c b/examples/mwalib-print-context.c
index dfb66a2..6df2ef3 100644
--- a/examples/mwalib-print-context.c
+++ b/examples/mwalib-print-context.c
@@ -39,7 +39,7 @@ int main(int argc, char *argv[])
     if (file_count == 1)
     {
         // Metafits only
-        if (mwalib_metafits_context_new(argv[1], CorrLegacy, &metafits_context, error_message, ERROR_MESSAGE_LEN) != EXIT_SUCCESS)
+        if (mwalib_metafits_context_new2(argv[1], &metafits_context, error_message, ERROR_MESSAGE_LEN) != EXIT_SUCCESS)
         {
             printf("Error getting metafits context: %s\n", error_message);
             exit(-1);
diff --git a/src/ffi/mod.rs b/src/ffi/mod.rs
index 1070c0b..2333721 100644
--- a/src/ffi/mod.rs
+++ b/src/ffi/mod.rs
@@ -185,14 +185,13 @@ fn ffi_array_to_boxed_slice<T>(v: Vec<T>) -> *mut T {
     }
 }
 
-/// Create and return a pointer to an `MetafitsContext` struct given only a metafits file
+/// Create and return a pointer to an `MetafitsContext` struct given only a metafits file and MWAVersion.
 ///
 /// # Arguments
 ///
 /// * `metafits_filename` - pointer to char* buffer containing the full path and filename of a metafits file.
 ///
 /// * `mwa_version` - enum providing mwalib with the intended mwa version which the metafits should be interpreted.
-///                   Pass 0 to get mwalib to detect the version from the MODE metafits keyword.
 ///
 /// * `out_metafits_context_ptr` - A Rust-owned populated `MetafitsContext` pointer. Free with `mwalib_metafits_context_free'.
 ///
@@ -222,16 +221,59 @@ pub unsafe extern "C" fn mwalib_metafits_context_new(
         .unwrap()
         .to_string();
 
-    // In C/FFI any value can be passed in, even 0
-    let int_mwa_version = mwa_version as u8;
+    let context = match MetafitsContext::new(&m, Some(mwa_version)) {
+        Ok(c) => c,
+        Err(e) => {
+            set_c_string(
+                &format!("{}", e),
+                error_message as *mut u8,
+                error_message_length,
+            );
+            // Return failure
+            return MWALIB_FAILURE;
+        }
+    };
 
-    let context = match MetafitsContext::new(
-        &m,
-        match int_mwa_version {
-            0 => None,
-            _ => Some(mwa_version),
-        },
-    ) {
+    *out_metafits_context_ptr = Box::into_raw(Box::new(context));
+
+    // Return success
+    MWALIB_SUCCESS
+}
+
+/// Create and return a pointer to an `MetafitsContext` struct given only a metafits file. Same as mwalib_metafits_context_new, but mwalib will guess the MWAVersion.
+///
+/// # Arguments
+///
+/// * `metafits_filename` - pointer to char* buffer containing the full path and filename of a metafits file.
+///
+/// * `out_metafits_context_ptr` - A Rust-owned populated `MetafitsContext` pointer. Free with `mwalib_metafits_context_free'.
+///
+/// * `error_message` - pointer to already allocated buffer for any error messages to be returned to the caller.
+///
+/// * `error_message_length` - length of error_message char* buffer.
+///
+///
+/// # Returns
+///
+/// * return MWALIB_SUCCESS on success, non-zero on failure
+///
+///
+/// # Safety
+/// * `error_message` *must* point to an already allocated `char*` buffer for any error messages.
+/// * Caller *must* call the `mwalib_metafits_context_free` function to release the rust memory.
+#[no_mangle]
+pub unsafe extern "C" fn mwalib_metafits_context_new2(
+    metafits_filename: *const c_char,
+    out_metafits_context_ptr: &mut *mut MetafitsContext,
+    error_message: *const c_char,
+    error_message_length: size_t,
+) -> i32 {
+    let m = CStr::from_ptr(metafits_filename)
+        .to_str()
+        .unwrap()
+        .to_string();
+
+    let context = match MetafitsContext::new(&m, None) {
         Ok(c) => c,
         Err(e) => {
             set_c_string(
diff --git a/src/ffi/test.rs b/src/ffi/test.rs
index d4e3876..395f321 100644
--- a/src/ffi/test.rs
+++ b/src/ffi/test.rs
@@ -327,6 +327,42 @@ fn test_mwalib_metafits_context_display() {
     }
 }
 
+#[test]
+fn test_mwalib_metafits_context_new_guess_mwa_version() {
+    let error_len: size_t = 128;
+    let error_message = CString::new(" ".repeat(error_len)).unwrap();
+    let error_message_ptr = error_message.as_ptr() as *const c_char;
+
+    let metafits_file =
+        CString::new("test_files/1101503312_1_timestep/1101503312.metafits").unwrap();
+    let metafits_file_ptr = metafits_file.as_ptr();
+
+    unsafe {
+        // Create a MetafitsContext
+        let mut metafits_context_ptr: *mut MetafitsContext = std::ptr::null_mut();
+        let retval = mwalib_metafits_context_new2(
+            metafits_file_ptr,
+            &mut metafits_context_ptr,
+            error_message_ptr,
+            error_len,
+        );
+
+        // Check return value of mwalib_metafits_context_new
+        assert_eq!(retval, 0, "mwalib_metafits_context_new failure");
+
+        // Check we got valid MetafitsContext pointer
+        let context_ptr = metafits_context_ptr.as_mut();
+        assert!(context_ptr.is_some());
+
+        let metafits_context = context_ptr.unwrap();
+
+        assert_eq!(
+            metafits_context.mwa_version.unwrap(),
+            MWAVersion::CorrLegacy
+        );
+    }
+}
+
 #[test]
 fn test_mwalib_metafits_context_display_null_ptr() {
     let metafits_context_ptr: *mut MetafitsContext = std::ptr::null_mut();
diff --git a/src/metafits_context/test.rs b/src/metafits_context/test.rs
index 7838b6f..1354691 100644
--- a/src/metafits_context/test.rs
+++ b/src/metafits_context/test.rs
@@ -378,6 +378,19 @@ fn test_populate_expected_coarse_channels_corr_mwaxv2() {
     }
 }
 
+#[test]
+fn test_metafits_context_new_guess_version() {
+    // Open the test metafits file
+    let metafits_filename = "test_files/1101503312_1_timestep/1101503312.metafits";
+
+    // Open a context and load in a test metafits
+    let result = MetafitsContext::new(&metafits_filename, None);
+    assert!(result.is_ok());
+
+    let context = result.unwrap();
+    assert_eq!(context.mwa_version.unwrap(), MWAVersion::CorrLegacy);
+}
+
 #[test]
 fn test_generate_expected_volt_filename_legacy_vcs() {
     // Open the test metafits file