diff --git a/src/bin/bat/main.rs b/src/bin/bat/main.rs
index 65129fa7..03fff166 100644
--- a/src/bin/bat/main.rs
+++ b/src/bin/bat/main.rs
@@ -86,6 +86,19 @@ pub fn list_languages(config: &Config) -> Result<()> {
         .filter(|syntax| !syntax.hidden && !syntax.file_extensions.is_empty())
         .cloned()
         .collect::<Vec<_>>();
+
+    for lang in languages.iter_mut() {
+        let lang_name = lang.name.clone();
+        lang.file_extensions.retain(|extension| {
+            let test_file = Path::new("test").with_extension(extension);
+            match config.syntax_mapping.get_syntax_for(test_file) {
+                Some(MappingTarget::MapTo(primary_lang)) => lang_name == primary_lang,
+                Some(MappingTarget::MapToUnknown) => true,
+                None => true,
+            }
+        });
+    }
+
     languages.sort_by_key(|lang| lang.name.to_uppercase());
 
     let configured_languages = get_syntax_mapping_to_paths(config.syntax_mapping.mappings());
diff --git a/src/syntax_mapping.rs b/src/syntax_mapping.rs
index 96ce7fc6..84558ede 100644
--- a/src/syntax_mapping.rs
+++ b/src/syntax_mapping.rs
@@ -24,6 +24,12 @@ impl<'a> SyntaxMapping<'a> {
         let mut mapping = Self::empty();
         mapping.insert("*.h", MappingTarget::MapTo("C++")).unwrap();
         mapping.insert("*.fs", MappingTarget::MapTo("F#")).unwrap();
+        mapping
+            .insert("*.js", MappingTarget::MapTo("JavaScript (Babel)"))
+            .unwrap();
+        mapping
+            .insert("*.sass", MappingTarget::MapTo("Sass"))
+            .unwrap();
         mapping
             .insert("build", MappingTarget::MapToUnknown)
             .unwrap();
@@ -92,14 +98,16 @@ impl<'a> SyntaxMapping<'a> {
             "*.swap",
             "*.target",
             "*.timer",
-        ].iter() {
-            mapping
-                .insert(glob, MappingTarget::MapTo("INI"))
-                .unwrap();
+        ]
+        .iter()
+        {
+            mapping.insert(glob, MappingTarget::MapTo("INI")).unwrap();
         }
 
         // pacman hooks
-        mapping.insert("*.hook", MappingTarget::MapTo("INI")).unwrap();
+        mapping
+            .insert("*.hook", MappingTarget::MapTo("INI"))
+            .unwrap();
 
         mapping
     }
@@ -117,7 +125,7 @@ impl<'a> SyntaxMapping<'a> {
         &self.mappings
     }
 
-    pub(crate) fn get_syntax_for(&self, path: impl AsRef<Path>) -> Option<MappingTarget<'a>> {
+    pub fn get_syntax_for(&self, path: impl AsRef<Path>) -> Option<MappingTarget<'a>> {
         let candidate = Candidate::new(path.as_ref());
         let candidate_filename = path.as_ref().file_name().map(Candidate::new);
         for (ref glob, ref syntax) in self.mappings.iter().rev() {