diff --git a/src/bin_compare.rs b/src/bin_compare.rs
index 40f0991c..4c1216b0 100644
--- a/src/bin_compare.rs
+++ b/src/bin_compare.rs
@@ -39,14 +39,14 @@ async fn main_body() -> Result<(), Box<dyn std::error::Error>> {
     let args = std::env::args().skip(1);
     if args.is_empty() {
         let org_contents = read_stdin_to_string()?;
-        if let Ok(true) = run_anonymous_compare(org_contents) {
+        if run_anonymous_compare(org_contents).await? {
         } else {
             Err("Diff results do not match.")?;
         }
         Ok(())
     } else {
         for arg in args {
-            if run_compare_on_file(arg)? {
+            if run_compare_on_file(arg).await? {
             } else {
                 Err("Diff results do not match.")?;
             }
diff --git a/src/bin_foreign_document_test.rs b/src/bin_foreign_document_test.rs
index ad9665c1..ccd7e6c4 100644
--- a/src/bin_foreign_document_test.rs
+++ b/src/bin_foreign_document_test.rs
@@ -222,7 +222,7 @@ impl TestConfig {
 impl SingleFile {
     async fn run_test(self) -> Result<SingleFileResult, JoinError> {
         let _permit = TEST_PERMITS.acquire().await.unwrap();
-        let result = silent_compare_on_file(&self.file_path);
+        let result = silent_compare_on_file(&self.file_path).await;
         Ok(SingleFileResult {
             name: self.name,
             file_path: self.file_path,
diff --git a/src/compare/compare.rs b/src/compare/compare.rs
index d58d5de4..c9aff87d 100644
--- a/src/compare/compare.rs
+++ b/src/compare/compare.rs
@@ -12,33 +12,33 @@ use crate::context::LocalFileAccessInterface;
 use crate::parser::parse_file_with_settings;
 use crate::parser::parse_with_settings;
 
-pub fn run_anonymous_compare<P: AsRef<str>>(
+pub async fn run_anonymous_compare<P: AsRef<str>>(
     org_contents: P,
 ) -> Result<bool, Box<dyn std::error::Error>> {
-    run_anonymous_compare_with_settings(org_contents, &GlobalSettings::default(), false)
+    run_anonymous_compare_with_settings(org_contents, &GlobalSettings::default(), false).await
 }
 
-pub fn run_compare_on_file<P: AsRef<Path>>(
+pub async fn run_compare_on_file<P: AsRef<Path>>(
     org_path: P,
 ) -> Result<bool, Box<dyn std::error::Error>> {
-    run_compare_on_file_with_settings(org_path, &GlobalSettings::default(), false)
+    run_compare_on_file_with_settings(org_path, &GlobalSettings::default(), false).await
 }
 
-pub fn silent_anonymous_compare<P: AsRef<str>>(
+pub async fn silent_anonymous_compare<P: AsRef<str>>(
     org_contents: P,
 ) -> Result<bool, Box<dyn std::error::Error>> {
-    run_anonymous_compare_with_settings(org_contents, &GlobalSettings::default(), true)
+    run_anonymous_compare_with_settings(org_contents, &GlobalSettings::default(), true).await
 }
 
-pub fn silent_compare_on_file<P: AsRef<Path>>(
+pub async fn silent_compare_on_file<P: AsRef<Path>>(
     org_path: P,
 ) -> Result<bool, Box<dyn std::error::Error>> {
-    run_compare_on_file_with_settings(org_path, &GlobalSettings::default(), true)
+    run_compare_on_file_with_settings(org_path, &GlobalSettings::default(), true).await
 }
 
-pub fn run_anonymous_compare_with_settings<P: AsRef<str>>(
+pub async fn run_anonymous_compare_with_settings<'g, 's, P: AsRef<str>>(
     org_contents: P,
-    global_settings: &GlobalSettings,
+    global_settings: &GlobalSettings<'g, 's>,
     silent: bool,
 ) -> Result<bool, Box<dyn std::error::Error>> {
     // TODO: This is a work-around to pretend that dos line endings do not exist. It would be better to handle the difference in line endings.
@@ -76,9 +76,9 @@ pub fn run_anonymous_compare_with_settings<P: AsRef<str>>(
     Ok(true)
 }
 
-pub fn run_compare_on_file_with_settings<P: AsRef<Path>>(
+pub async fn run_compare_on_file_with_settings<'g, 's, P: AsRef<Path>>(
     org_path: P,
-    global_settings: &GlobalSettings,
+    global_settings: &GlobalSettings<'g, 's>,
     silent: bool,
 ) -> Result<bool, Box<dyn std::error::Error>> {
     let org_path = org_path.as_ref();
diff --git a/src/context/file_access_interface.rs b/src/context/file_access_interface.rs
index d54c7cfd..2d93e637 100644
--- a/src/context/file_access_interface.rs
+++ b/src/context/file_access_interface.rs
@@ -1,7 +1,7 @@
 use std::fmt::Debug;
 use std::path::PathBuf;
 
-pub trait FileAccessInterface: Debug {
+pub trait FileAccessInterface: Sync + Debug {
     fn read_file(&self, path: &str) -> Result<String, std::io::Error>;
 }