diff --git a/package.json b/package.json
index 2038d42c..2294f733 100644
--- a/package.json
+++ b/package.json
@@ -19,7 +19,7 @@
     "url": "https://github.com/Microsoft/monaco-css/issues"
   },
   "devDependencies": {
-    "monaco-editor-core": "0.11.3",
+    "monaco-editor-core": "0.12.0",
     "monaco-languages": "1.0.0",
     "monaco-plugin-helpers": "^1.0.2",
     "requirejs": "^2.3.5",
diff --git a/src/languageFeatures.ts b/src/languageFeatures.ts
index 33904f91..cab6acfe 100644
--- a/src/languageFeatures.ts
+++ b/src/languageFeatures.ts
@@ -95,14 +95,14 @@ export class DiagnostcsAdapter {
 }
 
 
-function toSeverity(lsSeverity: number): monaco.Severity {
+function toSeverity(lsSeverity: number): monaco.MarkerSeverity {
 	switch (lsSeverity) {
-		case ls.DiagnosticSeverity.Error: return monaco.Severity.Error;
-		case ls.DiagnosticSeverity.Warning: return monaco.Severity.Warning;
-		case ls.DiagnosticSeverity.Information:
-		case ls.DiagnosticSeverity.Hint:
+		case ls.DiagnosticSeverity.Error: return monaco.MarkerSeverity.Error;
+		case ls.DiagnosticSeverity.Warning: return monaco.MarkerSeverity.Warning;
+		case ls.DiagnosticSeverity.Information: return monaco.MarkerSeverity.Info;
+		case ls.DiagnosticSeverity.Hint: return monaco.MarkerSeverity.Hint;
 		default:
-			return monaco.Severity.Info;
+			return monaco.MarkerSeverity.Info;
 	}
 }