diff --git a/src/server/protocol.ts b/src/server/protocol.ts
index 0bc9f3ac0c4b6..03e2be5be0f04 100644
--- a/src/server/protocol.ts
+++ b/src/server/protocol.ts
@@ -838,7 +838,6 @@ namespace ts.server.protocol {
     export interface EncodedSemanticClassificationsRequest extends FileRequest {
         arguments: EncodedSemanticClassificationsRequestArgs;
     }
-
     /**
      * Arguments for EncodedSemanticClassificationsRequest request.
      */
@@ -852,6 +851,10 @@ namespace ts.server.protocol {
          * Length of the span.
          */
         length: number;
+        /**
+         * Optional for backwards compat, use "2020" for modern LSP-like classifications
+         */
+        format?: ts.SemanticClassificationFormat
     }
 
     /**
@@ -3318,6 +3321,8 @@ namespace ts.server.protocol {
         Preserve = "Preserve",
         ReactNative = "ReactNative",
         React = "React",
+        ReactJSX = "ReactJSX",
+        ReactJSXDev = "ReactJSXDev",
     }
 
     export const enum ModuleKind {
@@ -3328,6 +3333,7 @@ namespace ts.server.protocol {
         System = "System",
         ES6 = "ES6",
         ES2015 = "ES2015",
+        ES2020 = "ES2020",
         ESNext = "ESNext"
     }
 
@@ -3351,6 +3357,7 @@ namespace ts.server.protocol {
         ES2018 = "ES2018",
         ES2019 = "ES2019",
         ES2020 = "ES2020",
+        JSON = "JSON",
         ESNext = "ESNext"
     }
 }
diff --git a/src/server/session.ts b/src/server/session.ts
index 73a86adf7c19e..e1afb046bc96e 100644
--- a/src/server/session.ts
+++ b/src/server/session.ts
@@ -1081,7 +1081,7 @@ namespace ts.server {
 
         private getEncodedSemanticClassifications(args: protocol.EncodedSemanticClassificationsRequestArgs) {
             const { file, project } = this.getFileAndProject(args);
-            return project.getLanguageService().getEncodedSemanticClassifications(file, args);
+            return project.getLanguageService().getEncodedSemanticClassifications(file, args, args.format);
         }
 
         private getProject(projectFileName: string | undefined): Project | undefined {
diff --git a/tests/baselines/reference/api/tsserverlibrary.d.ts b/tests/baselines/reference/api/tsserverlibrary.d.ts
index f721c4ce0a8da..668034e5d1b94 100644
--- a/tests/baselines/reference/api/tsserverlibrary.d.ts
+++ b/tests/baselines/reference/api/tsserverlibrary.d.ts
@@ -9084,7 +9084,9 @@ declare namespace ts.server.protocol {
         None = "None",
         Preserve = "Preserve",
         ReactNative = "ReactNative",
-        React = "React"
+        React = "React",
+        ReactJSX = "ReactJSX",
+        ReactJSXDev = "ReactJSXDev"
     }
     enum ModuleKind {
         None = "None",
@@ -9094,6 +9096,7 @@ declare namespace ts.server.protocol {
         System = "System",
         ES6 = "ES6",
         ES2015 = "ES2015",
+        ES2020 = "ES2020",
         ESNext = "ESNext"
     }
     enum ModuleResolutionKind {
@@ -9114,6 +9117,7 @@ declare namespace ts.server.protocol {
         ES2018 = "ES2018",
         ES2019 = "ES2019",
         ES2020 = "ES2020",
+        JSON = "JSON",
         ESNext = "ESNext"
     }
 }