diff --git a/asm-lsp/handle.rs b/asm-lsp/handle.rs
index 88fc70d0..8e759a9d 100644
--- a/asm-lsp/handle.rs
+++ b/asm-lsp/handle.rs
@@ -1,8 +1,6 @@
-use std::path::PathBuf;
-
 use anyhow::{anyhow, Result};
 use compile_commands::{CompilationDatabase, SourceFile};
-use log::{info, warn};
+use log::{error, info, warn};
 use lsp_server::{Connection, Message, Notification, Request, RequestId, Response};
 use lsp_types::{
     notification::{
@@ -20,10 +18,7 @@ use lsp_types::{
 use tree_sitter::Parser;
 
 use crate::{
-    apply_compile_cmd, get_comp_resp, get_compile_cmd_for_req, get_default_compile_cmd,
-    get_document_symbols, get_goto_def_resp, get_hover_resp, get_ref_resp, get_sig_help_resp,
-    get_word_from_pos_params, send_empty_resp, text_doc_change_to_ts_edit, CompletionItems, Config,
-    ConfigOptions, DocumentStore, NameToInstructionMap, RootConfig, ServerStore, TreeEntry,
+    apply_compile_cmd, get_comp_resp, get_compile_cmd_for_req, get_default_compile_cmd, get_document_symbols, get_goto_def_resp, get_hover_resp, get_ref_resp, get_sig_help_resp, get_word_from_pos_params, process_uri, send_empty_resp, text_doc_change_to_ts_edit, CompletionItems, Config, ConfigOptions, DocumentStore, NameToInstructionMap, RootConfig, ServerStore, TreeEntry, UriConversion
 };
 
 /// Handles `Request`s from the lsp client
@@ -533,14 +528,33 @@ pub fn handle_diagnostics(
     cfg: &Config,
     compile_cmds: &CompilationDatabase,
 ) -> Result<()> {
-    let req_source_path = PathBuf::from(uri.path().as_str());
+    let req_source_path = match process_uri(uri) {
+        UriConversion::Canonicalized(p) => p,
+        UriConversion::Unchecked(p) => {
+            error!(
+                "Failed to canonicalize request path {}, using {}",
+                uri.path().as_str(),
+                p.display()
+            );
+            p
+        }
+    };
 
     let source_entries = compile_cmds.iter().filter(|entry| match entry.file {
         SourceFile::File(ref file) => {
-            if file.is_absolute() {
-                file.eq(&req_source_path)
-            } else if let Ok(source_path) = file.canonicalize() {
-                source_path.eq(&req_source_path)
+            if let Ok(source_path) = file.canonicalize() {
+                // HACK: See comment inside `process_uri`
+                let cleaned_path = if cfg!(windows) {
+                    if let Some(tmp) = source_path.to_str().unwrap().strip_prefix("\\\\?\\") {
+                        warn!("Stripping Windows canonicalization prefix \"\\\\?\\\" from path");
+                        tmp.into()
+                    } else {
+                        source_path
+                    }
+                } else {
+                    source_path
+                };
+                cleaned_path.eq(&req_source_path)
             } else {
                 false
             }
diff --git a/asm-lsp/lsp.rs b/asm-lsp/lsp.rs
index 0992f017..5ded5cb0 100644
--- a/asm-lsp/lsp.rs
+++ b/asm-lsp/lsp.rs
@@ -176,7 +176,22 @@ pub fn process_uri(uri: &Uri) -> UriConversion {
     let Ok(path) = PathBuf::from_str(&clean_path);
     path.canonicalize()
         .map_or(UriConversion::Unchecked(path), |canonicalized| {
-            UriConversion::Canonicalized(canonicalized)
+            // HACK: On Windows, when a path is canonicalized, sometimes it gets prefixed
+            // with "\\?\" -- https://stackoverflow.com/questions/41233684/why-does-my-canonicalized-path-get-prefixed-with
+            // That's great and all, but it looks like common tools (like gcc) don't handle
+            // this correctly, and you get something like the following:
+            // Error: can't open //test.s for reading: No such file or directory
+            // The solution? Just cut out the prefix and hope that doesn't break anything else
+            if cfg!(windows) {
+                if let Some(tmp) = canonicalized.to_str().unwrap().strip_prefix("\\\\?\\") {
+                    warn!("Stripping Windows canonicalization prefix \"\\\\?\\\" from path");
+                    UriConversion::Canonicalized(tmp.into())
+                } else {
+                    UriConversion::Canonicalized(canonicalized)
+                }
+            } else {
+                UriConversion::Canonicalized(canonicalized)
+            }
         })
 }