diff --git a/.gitignore b/.gitignore
index d5c2f2f699..4f63471ede 100644
--- a/.gitignore
+++ b/.gitignore
@@ -27,6 +27,7 @@
 
 ## Byproducts of setting up and using the dev environment
 *.pyc
+*.tsbuildinfo
 package-lock.json
 
 /.vagrant
diff --git a/tsconfig.json b/tsconfig.json
index 51e4c368b6..534620cd2f 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -28,6 +28,9 @@
 
         /* Language and Environment */
         "target": "ESNext",
+
+        /* Projects */
+        "composite": true,
     },
     "exclude": [
         // Type stubs are not part of the top-level project.
diff --git a/web/shared/package.json b/web/shared/package.json
index fdeb639eee..40c863b1d5 100644
--- a/web/shared/package.json
+++ b/web/shared/package.json
@@ -3,7 +3,7 @@
   "version": "0.0.18",
   "license": "Apache-2.0",
   "scripts": {
-    "prepare": "rm -rf lib && tsc && cp src/*.flow lib",
+    "prepare": "tsc --build --clean && rm -rf lib && tsc && cp src/*.flow lib",
     "version": "tools/npm-version",
     "postversion": "tools/npm-postversion"
   },
diff --git a/web/shared/tsconfig.json b/web/shared/tsconfig.json
index 431a4a6165..f7abc5c80a 100644
--- a/web/shared/tsconfig.json
+++ b/web/shared/tsconfig.json
@@ -29,6 +29,9 @@
 
         /* Language and Environment */
         "target": "esnext",
+
+        /* Projects */
+        "composite": true,
     },
     "include": ["src"],
 }