diff --git a/.changeset/perfect-nails-smoke.md b/.changeset/perfect-nails-smoke.md
new file mode 100644
index 0000000000..823e9ac32c
--- /dev/null
+++ b/.changeset/perfect-nails-smoke.md
@@ -0,0 +1,6 @@
+---
+'@lit-labs/testing': patch
+'@lit/localize': patch
+---
+
+TS sources are now inlined in the JS source maps
diff --git a/packages/labs/testing/tsconfig.json b/packages/labs/testing/tsconfig.json
index c0df2dcc1c..8a6b3b36b3 100644
--- a/packages/labs/testing/tsconfig.json
+++ b/packages/labs/testing/tsconfig.json
@@ -14,6 +14,7 @@
     "declaration": true,
     "declarationMap": true,
     "sourceMap": true,
+    "inlineSources": true,
     "incremental": true,
     "tsBuildInfoFile": ".tsbuildinfo",
     "allowSyntheticDefaultImports": true,
diff --git a/packages/localize/package.json b/packages/localize/package.json
index 5615f0a459..ef1f7a50c2 100644
--- a/packages/localize/package.json
+++ b/packages/localize/package.json
@@ -61,6 +61,7 @@
   },
   "files": [
     "/lit-localize.d.ts",
+    "/lit-localize.d.ts.map",
     "/lit-localize.js",
     "/lit-localize.js.map",
     "/internal/",
diff --git a/packages/localize/tsconfig.json b/packages/localize/tsconfig.json
index 640a402014..8a6b3b36b3 100644
--- a/packages/localize/tsconfig.json
+++ b/packages/localize/tsconfig.json
@@ -12,7 +12,9 @@
     "rootDir": "src/",
     "outDir": ".",
     "declaration": true,
+    "declarationMap": true,
     "sourceMap": true,
+    "inlineSources": true,
     "incremental": true,
     "tsBuildInfoFile": ".tsbuildinfo",
     "allowSyntheticDefaultImports": true,