diff --git a/clients/ts/signalr-protocol-msgpack/package.json b/clients/ts/signalr-protocol-msgpack/package.json
index fe58caacd1..0dd9d8f47d 100644
--- a/clients/ts/signalr-protocol-msgpack/package.json
+++ b/clients/ts/signalr-protocol-msgpack/package.json
@@ -14,7 +14,7 @@
     "clean": "node ../node_modules/rimraf/bin.js ./dist",
     "build": "npm run clean && npm run build:lint && npm run build:esm && npm run build:cjs && npm run build:browser && npm run build:uglify",
     "build:lint": "node ../node_modules/tslint/bin/tslint -c ../tslint.json -p ./tsconfig.json",
-    "build:esm": "node ../node_modules/typescript/bin/tsc --project ./tsconfig.json --module es2015 --outDir ./dist/esm --target ES2015 -d",
+    "build:esm": "node ../node_modules/typescript/bin/tsc --project ./tsconfig.json --module es2015 --outDir ./dist/esm --target ES5 -d",
     "build:cjs": "node ../node_modules/typescript/bin/tsc --project ./tsconfig.json --module commonjs --outDir ./dist/cjs --target ES5",
     "build:browser": "node ../node_modules/rollup/bin/rollup -c",
     "build:uglify": "node ../node_modules/uglify-js/bin/uglifyjs --source-map \"url='signalr-protocol-msgpack.min.js.map',content='./dist/browser/signalr-protocol-msgpack.js.map'\" --comments -o ./dist/browser/signalr-protocol-msgpack.min.js ./dist/browser/signalr-protocol-msgpack.js",
diff --git a/clients/ts/signalr/package.json b/clients/ts/signalr/package.json
index 1f7d155f74..4674918d1a 100644
--- a/clients/ts/signalr/package.json
+++ b/clients/ts/signalr/package.json
@@ -14,7 +14,7 @@
     "clean": "node ../node_modules/rimraf/bin.js ./dist ./.rpt2_cache",
     "build": "npm run clean && npm run build:lint && npm run build:esm && npm run build:cjs && npm run build:browser && npm run build:uglify",
     "build:lint": "node ../node_modules/tslint/bin/tslint -c ../tslint.json -p ./tsconfig.json",
-    "build:esm": "node ../node_modules/typescript/bin/tsc --project ./tsconfig.json --module es2015 --outDir ./dist/esm --target ES2015 -d && node ./build/process-dts.js",
+    "build:esm": "node ../node_modules/typescript/bin/tsc --project ./tsconfig.json --module es2015 --outDir ./dist/esm --target ES5 -d && node ./build/process-dts.js",
     "build:cjs": "node ../node_modules/typescript/bin/tsc --project ./tsconfig.json --module commonjs --outDir ./dist/cjs --target ES5",
     "build:browser": "node ../node_modules/rollup/bin/rollup -c",
     "build:uglify": "node ../node_modules/uglify-js/bin/uglifyjs --source-map \"url='signalr.min.js.map',content='./dist/browser/signalr.js.map'\" --comments -o ./dist/browser/signalr.min.js ./dist/browser/signalr.js",