diff --git a/src/cli/root-option-value.test.ts b/src/cli/root-option-value.test.ts
new file mode 100644
index 00000000000..63c445f80b1
--- /dev/null
+++ b/src/cli/root-option-value.test.ts
@@ -0,0 +1,29 @@
+import { describe, expect, it } from "vitest";
+import { takeCliRootOptionValue } from "./root-option-value.js";
+
+describe("takeCliRootOptionValue", () => {
+  it("preserves equals signs after the first separator", () => {
+    expect(takeCliRootOptionValue("--token=abc=def", undefined)).toEqual({
+      value: "abc=def",
+      consumedNext: false,
+    });
+    expect(takeCliRootOptionValue("--token=abc==", undefined)).toEqual({
+      value: "abc==",
+      consumedNext: false,
+    });
+  });
+
+  it("treats empty inline values as missing", () => {
+    expect(takeCliRootOptionValue("--token=", "fallback")).toEqual({
+      value: null,
+      consumedNext: false,
+    });
+  });
+
+  it("continues to consume the next token for space-separated values", () => {
+    expect(takeCliRootOptionValue("--token", "abc=def")).toEqual({
+      value: "abc=def",
+      consumedNext: true,
+    });
+  });
+});
diff --git a/src/cli/root-option-value.ts b/src/cli/root-option-value.ts
index b4adf8d0644..5db55cc5fbd 100644
--- a/src/cli/root-option-value.ts
+++ b/src/cli/root-option-value.ts
@@ -8,7 +8,7 @@ export function takeCliRootOptionValue(
   consumedNext: boolean;
 } {
   if (raw.includes("=")) {
-    const [, value] = raw.split("=", 2);
+    const value = raw.slice(raw.indexOf("=") + 1);
     const trimmed = (value ?? "").trim();
     return { value: trimmed || null, consumedNext: false };
   }