diff --git a/package.json b/package.json
index d5071a70..2a043a85 100644
--- a/package.json
+++ b/package.json
@@ -44,7 +44,7 @@
     "glob": "^7.0.5",
     "gulp": "^3.9.1",
     "gulp-cli": "^1.2.2",
-    "gulp-sourcemaps": "^1.9.1",
+    "gulp-sourcemaps": "1.9.1",
     "gulp-typescript": "^3.1.3",
     "jsdoc": "3.4.3",
     "merge-stream": "^1.0.1",