diff --git a/src/formatter/clang.rs b/src/formatter/clang.rs
index d2e72d5..08e54c1 100644
--- a/src/formatter/clang.rs
+++ b/src/formatter/clang.rs
@@ -85,13 +85,14 @@ impl ClangFormatter {
         Some(p)
     }
 
-    fn get_command(&self, u: &Path) -> Command {
+    fn get_command(&self, f: &str, u: &Path) -> Option<Command> {
         let mut c = Command::new(self.path.as_str());
         if let Some(wd) = self.working_dir.as_ref() {
             c.current_dir(wd.as_str());
         }
-        c.args([u.to_str().unwrap(), "--output-replacements-xml"]);
-        c
+        c.stdin(File::open(u).ok()?);
+        c.args(["--output-replacements-xml", format!("--assume-filename={f}").as_str()]);
+        Some(c)
     }
 
     fn output_to_textedit(&self, output: &str, content: &str) -> Option<Vec<TextEdit>> {
@@ -107,9 +108,10 @@ impl ClangFormatter {
 }
 
 impl ProtoFormatter for ClangFormatter {
-    fn format_document(&self, content: &str) -> Option<Vec<TextEdit>> {
+    fn format_document(&self, filename: &str, content: &str) -> Option<Vec<TextEdit>> {
         let p = self.get_temp_file_path(content)?;
-        let output = self.get_command(p.as_ref()).output().ok()?;
+        let mut cmd = self.get_command(filename, p.as_ref())?;
+        let output = cmd.output().ok()?;
         if !output.status.success() {
             tracing::error!(
                 status = output.status.code(),
@@ -120,12 +122,12 @@ impl ProtoFormatter for ClangFormatter {
         self.output_to_textedit(&String::from_utf8_lossy(&output.stdout), content)
     }
 
-    fn format_document_range(&self, r: &Range, content: &str) -> Option<Vec<TextEdit>> {
+    fn format_document_range(&self, r: &Range, filename: &str, content: &str) -> Option<Vec<TextEdit>> {
         let p = self.get_temp_file_path(content)?;
         let start = r.start.line + 1;
         let end = r.end.line + 1;
         let output = self
-            .get_command(p.as_ref())
+            .get_command(filename, p.as_ref())?
             .args(["--lines", format!("{start}:{end}").as_str()])
             .output()
             .ok()?;
diff --git a/src/formatter/mod.rs b/src/formatter/mod.rs
index 67f6913..d5e1993 100644
--- a/src/formatter/mod.rs
+++ b/src/formatter/mod.rs
@@ -3,6 +3,6 @@ use async_lsp::lsp_types::{Range, TextEdit};
 pub mod clang;
 
 pub trait ProtoFormatter: Sized {
-    fn format_document(&self, content: &str) -> Option<Vec<TextEdit>>;
-    fn format_document_range(&self, r: &Range, content: &str) -> Option<Vec<TextEdit>>;
+    fn format_document(&self, filename: &str, content: &str) -> Option<Vec<TextEdit>>;
+    fn format_document_range(&self, r: &Range, filename: &str, content: &str) -> Option<Vec<TextEdit>>;
 }
diff --git a/src/lsp.rs b/src/lsp.rs
index 3674d43..0d9b59a 100644
--- a/src/lsp.rs
+++ b/src/lsp.rs
@@ -375,7 +375,7 @@ impl LanguageServer for ProtoLanguageServer {
         let response = self
             .state
             .get_formatter()
-            .and_then(|f| f.format_document(content.as_str()));
+            .and_then(|f| f.format_document(uri.path(), content.as_str()));
 
         Box::pin(async move { Ok(response) })
     }
@@ -390,7 +390,7 @@ impl LanguageServer for ProtoLanguageServer {
         let response = self
             .state
             .get_formatter()
-            .and_then(|f| f.format_document_range(&params.range, content.as_str()));
+            .and_then(|f| f.format_document_range(&params.range, uri.path(), content.as_str()));
 
         Box::pin(async move { Ok(response) })
     }