diff --git a/grammars.yml b/grammars.yml
index 10361eef..816c0b16 100644
--- a/grammars.yml
+++ b/grammars.yml
@@ -408,3 +408,5 @@ https://github.com/vmg/zephir-sublime:
 - source.php.zephir
 https://github.com/whitequark/llvm.tmbundle:
 - source.llvm
+https://github.com/lsf37/Isabelle.tmbundle:
+- source.isabelle.theory
diff --git a/lib/linguist/languages.yml b/lib/linguist/languages.yml
index 82ce55ec..56fdfea7 100644
--- a/lib/linguist/languages.yml
+++ b/lib/linguist/languages.yml
@@ -1211,7 +1211,7 @@ Isabelle:
   color: "#fdcd00"
   extensions:
   - .thy
-  tm_scope: none
+  tm_scope: source.isabelle.theory
 
 J:
   type: programming