diff --git a/package-lock.json b/package-lock.json
index e8cae936..73f6c81e 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -27,7 +27,8 @@
         "chai-as-promised": "^7.1.1",
         "chai-subset": "^1.6.0",
         "sqlite3": "^5.0.0",
-        "ts-jest": "^27.0.2"
+        "ts-jest": "^27.0.2",
+        "typescript": "^4.3.5"
       }
     },
     "bookshop": {
@@ -17830,7 +17831,6 @@
       "resolved": "https://registry.npmjs.org/typescript/-/typescript-4.3.5.tgz",
       "integrity": "sha512-DqQgihaQ9cUrskJo9kIyW/+g0Vxsk8cDtZ52a3NGh0YNTfpUSArXSohyUGnvbPazEPLu398C0UxmKSOrPumUzA==",
       "dev": true,
-      "peer": true,
       "bin": {
         "tsc": "bin/tsc",
         "tsserver": "bin/tsserver"
@@ -31634,8 +31634,7 @@
       "version": "4.3.5",
       "resolved": "https://registry.npmjs.org/typescript/-/typescript-4.3.5.tgz",
       "integrity": "sha512-DqQgihaQ9cUrskJo9kIyW/+g0Vxsk8cDtZ52a3NGh0YNTfpUSArXSohyUGnvbPazEPLu398C0UxmKSOrPumUzA==",
-      "dev": true,
-      "peer": true
+      "dev": true
     },
     "unbox-primitive": {
       "version": "1.0.1",
diff --git a/package.json b/package.json
index ca2f38ab..d3942295 100644
--- a/package.json
+++ b/package.json
@@ -23,7 +23,8 @@
     "chai-as-promised": "^7.1.1",
     "chai-subset": "^1.6.0",
     "sqlite3": "^5.0.0",
-    "ts-jest": "^27.0.2"
+    "ts-jest": "^27.0.2",
+    "typescript": "^4.3.5"
   },
   "scripts": {
     "cleanup": "rm -rf node_modules && rm -rf */node_modules && rm -rf */*/node_modules",
@@ -47,7 +48,9 @@
       "ts-jest": {
         "diagnostics": {
           "_comment": "see https://githubmemory.com/repo/kulshekhar/ts-jest/issues/2722",
-          "ignoreCodes": [151001]
+          "ignoreCodes": [
+            151001
+          ]
         }
       }
     }