diff --git a/common/models/templates/build.sh b/common/models/templates/build.sh
index b5ae2a8c23..0fe305ca5a 100755
--- a/common/models/templates/build.sh
+++ b/common/models/templates/build.sh
@@ -18,8 +18,9 @@ cd "$(dirname "$THIS_SCRIPT")"
 ################################ Main script ################################
 
 builder_describe "Builds the predictive-text model template implementation module" \
-  "@../../web/keyman-version" \
-  "@../wordbreakers" \
+  "@/common/web/keyman-version" \
+  "@/common/web/tslib" \
+  "@/common/models/wordbreakers" \
   "clean" \
   "configure" \
   "build" \
diff --git a/common/models/templates/tsconfig.json b/common/models/templates/tsconfig.json
index 9284bddd20..7ff603ef29 100644
--- a/common/models/templates/tsconfig.json
+++ b/common/models/templates/tsconfig.json
@@ -7,6 +7,7 @@
     "moduleResolution": "node16",
     "sourceMap": true,
     "sourceRoot": "/common/models/templates/src",
+    "importHelpers": true,
     "inlineSources": true,
     "strict": true,
     "lib": ["es6"],
diff --git a/common/models/wordbreakers/src/default/index.ts b/common/models/wordbreakers/src/default/index.ts
index 65dbd0faf0..20e159ed19 100644
--- a/common/models/wordbreakers/src/default/index.ts
+++ b/common/models/wordbreakers/src/default/index.ts
@@ -431,7 +431,7 @@ function findBoundaries(text: string, options?: DefaultWordBreakerOptions): numb
     }
     // Do not break across certain punctuation
     // WB6: (Don't break before apostrophes in contractions)
-    const SET_ALL_MIDLETTER = [WordBreakProperty.MidLetter, ...SET_MIDNUMLETQ];
+    const SET_ALL_MIDLETTER = [WordBreakProperty.MidLetter].concat(SET_MIDNUMLETQ);
     if(state.match(null, SET_AHLETTER, SET_ALL_MIDLETTER, SET_AHLETTER)) {
       continue;
     }
@@ -474,7 +474,7 @@ function findBoundaries(text: string, options?: DefaultWordBreakerOptions): numb
     }
     // Do not break within sequences, such as 3.2, 3,456.789
     // WB11
-    const SET_ALL_MIDNUM = [WordBreakProperty.MidNum, ...SET_MIDNUMLETQ];
+    const SET_ALL_MIDNUM = [WordBreakProperty.MidNum].concat(SET_MIDNUMLETQ);
     if(state.match([WordBreakProperty.Numeric], SET_ALL_MIDNUM, [WordBreakProperty.Numeric], null)) {
       continue;
     }
@@ -488,9 +488,7 @@ function findBoundaries(text: string, options?: DefaultWordBreakerOptions): numb
     }
     // Do not break from extenders (e.g., U+202F NARROW NO-BREAK SPACE)
     // WB13a
-    const SET_NUM_KAT_LET = [WordBreakProperty.Katakana,
-                              WordBreakProperty.Numeric,
-                              ...SET_AHLETTER];
+    const SET_NUM_KAT_LET = [WordBreakProperty.Katakana, WordBreakProperty.Numeric].concat(SET_AHLETTER);
     if(state.match(null, SET_NUM_KAT_LET, [WordBreakProperty.ExtendNumLet], null)) {
       continue;
     }
diff --git a/common/models/wordbreakers/tsconfig.json b/common/models/wordbreakers/tsconfig.json
index 6c029da40a..549b7410d6 100644
--- a/common/models/wordbreakers/tsconfig.json
+++ b/common/models/wordbreakers/tsconfig.json
@@ -8,6 +8,7 @@
     "moduleResolution": "Node16",
     "declaration": true,
     "sourceMap": true,
+    "importHelpers": true,
     "inlineSources": true,
     "sourceRoot": "/common/models/wordbreakers/src",
     "strict": true,
diff --git a/common/web/lm-worker/build-bundler.js b/common/web/lm-worker/build-bundler.js
index 605ff3cd40..eb7bb5ea41 100644
--- a/common/web/lm-worker/build-bundler.js
+++ b/common/web/lm-worker/build-bundler.js
@@ -6,8 +6,8 @@
  */
 
 import esbuild from 'esbuild';
-import { spawn } from 'child_process';
 import fs from 'fs';
+import { determineNeededDowncompileHelpers, buildTslibTreeshaker } from '@keymanapp/tslib/esbuild-tools';
 
 /*
  * Refer to https://github.com/microsoft/TypeScript/issues/13721#issuecomment-307259227 -
@@ -92,7 +92,12 @@ await esbuild.build({
   target: "es5"
 });
 
+// The one that's actually a component of our releases.
+
 const embeddedWorkerBuildOptions = {
+  alias: {
+    'tslib': '@keymanapp/tslib'
+  },
   bundle: true,
   sourcemap: true,
   format: "iife",
@@ -106,6 +111,10 @@ const embeddedWorkerBuildOptions = {
   target: "es5"
 }
 
+// Prepare the needed setup for `tslib` treeshaking.
+const unusedHelpers = await determineNeededDowncompileHelpers(embeddedWorkerBuildOptions);
+embeddedWorkerBuildOptions.plugins = [buildTslibTreeshaker(unusedHelpers), ...embeddedWorkerBuildOptions.plugins];
+
 // Direct-use version
 await esbuild.build(embeddedWorkerBuildOptions);
 
diff --git a/common/web/lm-worker/build.sh b/common/web/lm-worker/build.sh
index 75a72df12d..82fba9bb39 100755
--- a/common/web/lm-worker/build.sh
+++ b/common/web/lm-worker/build.sh
@@ -28,6 +28,7 @@ WORKER_OUTPUT_FILENAME=build/lib/worker-main.js
 builder_describe \
   "Compiles the Language Modeling Layer for common use in predictive text and autocorrective applications." \
   "@/common/web/keyman-version" \
+  "@/common/web/tslib" \
   "@/common/models/wordbreakers" \
   "@/common/models/templates" \
   "@/common/tools/sourcemap-path-remapper" \
diff --git a/common/web/lm-worker/tsconfig.json b/common/web/lm-worker/tsconfig.json
index 551f1645a9..2fdda0135a 100644
--- a/common/web/lm-worker/tsconfig.json
+++ b/common/web/lm-worker/tsconfig.json
@@ -5,7 +5,8 @@
     "allowJs": false,
     "declaration": true,
     "module": "es6",
-    "moduleResolution": "node",
+    "moduleResolution": "node16",
+    "importHelpers": true,
     "inlineSourceMap": true,
     "inlineSources": true,
     "sourceRoot": "/common/web/lm-worker/src",