diff --git a/bun.lock b/bun.lock
index e46f438..ff79da0 100644
--- a/bun.lock
+++ b/bun.lock
@@ -26,7 +26,7 @@
         "stackmap": "./dist/cli.js",
       },
       "dependencies": {
-        "elkjs": "^0.12.0",
+        "elkjs": "0.12.0",
       },
       "devDependencies": {
         "@playwright/test": "^1.63.0",
@@ -47,7 +47,7 @@
       "version": "0.0.0",
       "dependencies": {
         "@stackmap/core": "workspace:*",
-        "elkjs": "^0.12.0",
+        "elkjs": "0.12.0",
       },
     },
     "packages/schema": {
diff --git a/packages/cli/package.json b/packages/cli/package.json
index 13a02ea..f27653b 100644
--- a/packages/cli/package.json
+++ b/packages/cli/package.json
@@ -49,7 +49,7 @@
     "prepack": "bun run build && node scripts/prepack.mjs"
   },
   "dependencies": {
-    "elkjs": "^0.12.0"
+    "elkjs": "0.12.0"
   },
   "devDependencies": {
     "@playwright/test": "^1.63.0",
diff --git a/packages/cli/test/skill.test.ts b/packages/cli/test/skill.test.ts
index 4d35725..1e1b1f4 100644
--- a/packages/cli/test/skill.test.ts
+++ b/packages/cli/test/skill.test.ts
@@ -25,6 +25,13 @@ describe('skill ↔ CLI version', () => {
 });
 
 describe('package.json', () => {
+  it('pins elkjs exactly, and to the version the layout package uses, so a CLI version always gives the same layout', () => {
+    const dep = (p: string) => (JSON.parse(readFileSync(new URL(p, import.meta.url), 'utf8')) as { dependencies: Record<string, string> }).dependencies.elkjs;
+    const cli = dep('../package.json');
+    expect(cli).toMatch(/^\d+\.\d+\.\d+$/);
+    expect(dep('../../layout/package.json')).toBe(cli);
+  });
+
   it('names every diagram kind in its npm keywords, so a search for any of them finds the package', () => {
     const { keywords } = JSON.parse(readFileSync(new URL('../package.json', import.meta.url), 'utf8')) as { keywords: string[] };
     for (const kind of DIAGRAM_KINDS) expect(keywords, kind).toContain(kind);
diff --git a/packages/layout/package.json b/packages/layout/package.json
index 07dd8e8..325bd4c 100644
--- a/packages/layout/package.json
+++ b/packages/layout/package.json
@@ -13,6 +13,6 @@
   },
   "dependencies": {
     "@stackmap/core": "workspace:*",
-    "elkjs": "^0.12.0"
+    "elkjs": "0.12.0"
   }
 }