diff --git a/grammars.yml b/grammars.yml
index 511e6a24..bd2bdd8e 100644
--- a/grammars.yml
+++ b/grammars.yml
@@ -412,5 +412,7 @@ 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
 https://github.com/eregon/oz-tmbundle:
 - source.oz
diff --git a/lib/linguist/languages.yml b/lib/linguist/languages.yml
index 66b3de71..da18b25a 100644
--- a/lib/linguist/languages.yml
+++ b/lib/linguist/languages.yml
@@ -1223,7 +1223,7 @@ Isabelle:
   color: "#fdcd00"
   extensions:
   - .thy
-  tm_scope: none
+  tm_scope: source.isabelle.theory
 
 J:
   type: programming