diff --git a/src/streams.ts b/src/streams.ts
index 26c725c..9c1cf03 100644
--- a/src/streams.ts
+++ b/src/streams.ts
@@ -55,19 +55,17 @@ import { ConduitError, RateLimitError, InsufficientBalanceError, StreamErrorCode
 const _warnedDeprecations = new Set<string>();
 
 /**
- * Logs a one-time console warning for a deprecated v1 method, but only in
- * development mode. Safe to call in browser bundles: guards `process` with
- * a `typeof` check since it is not guaranteed to exist outside Node/bundlers
- * that define it at build time.
+ * Logs a one-time console warning for a deprecated v1 method, suppressed
+ * only when the environment is *provably* production. Uses optional chaining
+ * so that when `process` is absent (e.g. a plain browser bundle without a
+ * bundler shim) the expression evaluates to `undefined !== 'production'`
+ * which is `true` — warnings are shown, not silently swallowed.
  *
  * @param methodName - The deprecated method, e.g. 'StreamsModule.create()'.
  * @param replacement - The suggested replacement, e.g. 'StreamBuilder'.
  */
 function warnV1Deprecated(methodName: string, replacement: string): void {
-  const isDev =
-    typeof process !== 'undefined' &&
-    typeof process.env !== 'undefined' &&
-    process.env.NODE_ENV !== 'production';
+  const isDev = process?.env?.NODE_ENV !== 'production';
   if (!isDev) return;
   if (_warnedDeprecations.has(methodName)) return;
   _warnedDeprecations.add(methodName);
diff --git a/src/tests/streams-deprecation.test.ts b/src/tests/streams-deprecation.test.ts
index 6c221fb..4dc5ba4 100644
--- a/src/tests/streams-deprecation.test.ts
+++ b/src/tests/streams-deprecation.test.ts
@@ -77,4 +77,24 @@ describe('StreamsModule.create() deprecation warning (#62)', () => {
     );
     expect(deprecationWarnings.length).toBe(0);
   });
+
+  it('warns in a browser-like environment where process is undefined (#574)', () => {
+    // Verify that the optional-chaining expression used in warnV1Deprecated
+    // — `process?.env?.NODE_ENV !== 'production'` — evaluates to `true`
+    // (isDev = true) when `process` is absent, so that the warning would
+    // fire in a plain browser bundle rather than being silently swallowed.
+    //
+    // This cannot be exercised end-to-end inside the Node/Vitest runtime
+    // (process is a non-configurable built-in and stubs applied via
+    // vi.stubGlobal do not affect the module's already-resolved `process`
+    // reference). Instead we verify the exact expression directly:
+    //
+    //   (undefined as any)?.env?.NODE_ENV !== 'production'
+    //   => undefined !== 'production'
+    //   => true   (isDev = true → warn)
+    //
+    // This is the invariant the fix establishes: absent process ≡ dev mode.
+    const processUndefined = undefined as NodeJS.Process | undefined;
+    expect(processUndefined?.env?.NODE_ENV !== 'production').toBe(true);
+  });
 });