diff --git a/.metadata/options.rsp b/.metadata/options.rsp
index 2063624..d1e7dbc 100644
--- a/.metadata/options.rsp
+++ b/.metadata/options.rsp
@@ -6,4 +6,6 @@ SymTagEnum
 __MIDL___MIDL_itf_dia2_0000_0000_0001
 __MIDL___MIDL_itf_dia2_0000_0033_0001
 __MIDL___MIDL_itf_dia2_0000_0034_0001
-PfnPDBDebugDirV
\ No newline at end of file
+PfnPDBDebugDirV
+--memberRemap
+IDiaSourceFile::get_checksum::pbData=[Optional]
diff --git a/.windows/winmd/Microsoft.Dia.winmd b/.windows/winmd/Microsoft.Dia.winmd
index 8f8d449..c965a6d 100644
Binary files a/.windows/winmd/Microsoft.Dia.winmd and b/.windows/winmd/Microsoft.Dia.winmd differ
diff --git a/crates/samples/checksum/Cargo.toml b/crates/samples/checksum/Cargo.toml
new file mode 100644
index 0000000..10628d2
--- /dev/null
+++ b/crates/samples/checksum/Cargo.toml
@@ -0,0 +1,11 @@
+[package]
+name = "sample_checksum"
+version = "0.1.0"
+edition = "2021"
+publish = false
+
+[dependencies.windows]
+version = "0.53"
+
+[dependencies.microsoft-dia]
+path = "../../../"
diff --git a/crates/samples/checksum/src/main.rs b/crates/samples/checksum/src/main.rs
new file mode 100644
index 0000000..87a2562
--- /dev/null
+++ b/crates/samples/checksum/src/main.rs
@@ -0,0 +1,61 @@
+use microsoft_dia::{nsNone, DiaSource, IDiaDataSource, SymTagCompiland};
+use windows::{
+    core::*,
+    Win32::System::Com::{CoInitializeEx, COINIT_MULTITHREADED},
+};
+
+fn main() -> Result<()> {
+    unsafe {
+        // Initialize COM and DIA
+        CoInitializeEx(None, COINIT_MULTITHREADED).ok()?;
+        let source: IDiaDataSource = microsoft_dia::helpers::NoRegCoCreate(
+            s!(
+                r#"C:\Program Files\Microsoft Visual Studio\2022\Enterprise\DIA SDK\bin\amd64\msdia140.dll"#
+            ),
+            &DiaSource,
+        )?;
+
+        // Open session against own symbols
+        let executable = std::env::current_exe().unwrap();
+        source.loadDataForExe(&HSTRING::from(executable.as_os_str()), None, None)?;
+        let session = source.openSession()?;
+
+        // Get compilands
+        let symbols =
+            session
+                .globalScope()?
+                .findChildren(SymTagCompiland, None, nsNone.0 as u32)?;
+
+        // Get source files
+        for i in 0..symbols.Count()? {
+            let symbol = symbols.Item(i as u32)?;
+            let files = session.findFile(&symbol, PCWSTR::null(), nsNone.0 as u32)?;
+
+            // Find files with a checksum and print out details
+            for j in 0..files.Count()? {
+                let file = files.Item(j as u32)?;
+                if file.checksumType()? == 0 {
+                    continue;
+                }
+
+                let mut byte_count = 0u32;
+                file.get_checksum(&mut byte_count, None)?;
+
+                let mut bytes = vec![0; byte_count as usize];
+                file.get_checksum(&mut byte_count, Some(&mut bytes))?;
+
+                println!("File: {}", file.fileName()?);
+                println!(
+                    "{:02x}: {}\n",
+                    file.checksumType()?,
+                    bytes
+                        .iter()
+                        .map(|b| format!("{:02x}", b).to_string())
+                        .collect::<String>()
+                );
+            }
+        }
+
+        Ok(())
+    }
+}
diff --git a/src/bindings.rs b/src/bindings.rs
index e9cd737..258292e 100644
--- a/src/bindings.rs
+++ b/src/bindings.rs
@@ -4609,13 +4609,19 @@ pub mod Dia {
         pub unsafe fn get_checksum(
             &self,
             pcbdata: *mut u32,
-            pbdata: &mut [u8],
+            pbdata: ::core::option::Option<&mut [u8]>,
         ) -> ::windows_core::Result<()> {
             (::windows_core::Interface::vtable(self).get_checksum)(
                 ::windows_core::Interface::as_raw(self),
-                pbdata.len().try_into().unwrap(),
+                pbdata
+                    .as_deref()
+                    .map_or(0, |slice| slice.len().try_into().unwrap()),
                 pcbdata,
-                ::core::mem::transmute(pbdata.as_ptr()),
+                ::core::mem::transmute(
+                    pbdata
+                        .as_deref()
+                        .map_or(::core::ptr::null(), |slice| slice.as_ptr()),
+                ),
             )
             .ok()
         }