diff --git a/.changeset/calm-tools-remember.md b/.changeset/calm-tools-remember.md
new file mode 100644
index 00000000000..3fdf6410e03
--- /dev/null
+++ b/.changeset/calm-tools-remember.md
@@ -0,0 +1,5 @@
+---
+"effect": patch
+---
+
+Preserve equals signs in inline CLI option values after the first separator.
diff --git a/packages/effect/src/unstable/cli/internal/lexer.ts b/packages/effect/src/unstable/cli/internal/lexer.ts
index 3d09d117718..40e47641bbf 100644
--- a/packages/effect/src/unstable/cli/internal/lexer.ts
+++ b/packages/effect/src/unstable/cli/internal/lexer.ts
@@ -47,8 +47,14 @@ const lexTokens = (args: ReadonlyArray<string>): ReadonlyArray<Token> => {
     if (!arg.startsWith("-")) {
       tokens.push({ _tag: "Value", value: arg })
     } else if (arg.startsWith("--")) {
-      const [name, value] = arg.slice(2).split("=", 2)
-      tokens.push({ _tag: "LongOption", name, raw: arg, value })
+      const equalIndex = arg.indexOf("=")
+      if (equalIndex !== -1) {
+        const name = arg.slice(2, equalIndex)
+        const value = arg.slice(equalIndex + 1)
+        tokens.push({ _tag: "LongOption", name, raw: arg, value })
+      } else {
+        tokens.push({ _tag: "LongOption", name: arg.slice(2), raw: arg })
+      }
     } else if (arg.length > 1) {
       const flags = arg.slice(1)
       const equalIndex = flags.indexOf("=")
diff --git a/packages/effect/test/unstable/cli/Lexer.test.ts b/packages/effect/test/unstable/cli/Lexer.test.ts
new file mode 100644
index 00000000000..7d55f26815e
--- /dev/null
+++ b/packages/effect/test/unstable/cli/Lexer.test.ts
@@ -0,0 +1,15 @@
+import { assert, describe, it } from "@effect/vitest"
+import * as Lexer from "effect/unstable/cli/internal/lexer"
+
+describe("Lexer", () => {
+  it("preserves every equals sign in a long option's inline value", () => {
+    const result = Lexer.lex(["--query=left=right"])
+
+    assert.deepStrictEqual(result.tokens, [{
+      _tag: "LongOption",
+      name: "query",
+      raw: "--query=left=right",
+      value: "left=right"
+    }])
+  })
+})