diff --git a/examples/ffi-jni-env-03-tl-fallback.sx b/examples/ffi-jni-env-03-tl-fallback.sx
new file mode 100644
index 0000000..e7a1f12
--- /dev/null
+++ b/examples/ffi-jni-env-03-tl-fallback.sx
@@ -0,0 +1,37 @@
+// Phase 2 step 2.16c (PLAN-FFI.md): xfail then green for the
+// thread-local env fallback in `#jni_call`. When a `#jni_call` site
+// has its env arg omitted AND no `#jni_env` block exists in the same
+// function (e.g., we're in a helper called FROM such a block), the
+// compiler emits a TL load instead of a sema error.
+//
+// The TL is pushed/popped by the `#jni_env(env) { ... }` enclosing
+// scope at runtime; helpers that don't see the lexical scope still
+// pick up the env transparently. Cross-function callers no longer
+// need to thread env as an explicit parameter.
+//
+// Today (2.16b only): lowerJniCall errors when env is omitted and
+// jni_env_stack is empty, because TL emission isn't wired yet.
+
+#import "modules/std.sx";
+
+g_should_call : bool = false;
+
+// Helper fn — no `#jni_env` block in scope. Without TL fallback this
+// errors because the omitted env can't be resolved.
+helper :: (target: *void) {
+    #jni_call(void)(target, "noop", "()V");
+}
+
+unused :: (env: *void, target: *void) {
+    #jni_env(env) {
+        helper(target);
+    }
+}
+
+main :: () -> s32 {
+    if g_should_call {
+        unused(null, null);
+    }
+    print("ok\n");
+    0;
+}
diff --git a/tests/expected/ffi-jni-env-03-tl-fallback.exit b/tests/expected/ffi-jni-env-03-tl-fallback.exit
new file mode 100644
index 0000000..d00491f
--- /dev/null
+++ b/tests/expected/ffi-jni-env-03-tl-fallback.exit
@@ -0,0 +1 @@
+1
diff --git a/tests/expected/ffi-jni-env-03-tl-fallback.txt b/tests/expected/ffi-jni-env-03-tl-fallback.txt
new file mode 100644
index 0000000..e8dc2da
--- /dev/null
+++ b/tests/expected/ffi-jni-env-03-tl-fallback.txt
@@ -0,0 +1,14 @@
+LLVM verification failed: Load operand must be a pointer.
+  %jni.ifs = load ptr, i64 undef, align 8
+Call parameter type does not match function signature!
+i64 undef
+ ptr  %jni.cls = call ptr %jni.GetObjectClass(i64 undef, ptr %load)
+Call parameter type does not match function signature!
+i64 undef
+ ptr  %jni.global.cls = call ptr %jni.NewGlobalRef(i64 undef, ptr %jni.cls)
+Call parameter type does not match function signature!
+i64 undef
+ ptr  %jni.fresh.mid = call ptr %jni.GetMethodID(i64 undef, ptr %jni.global.cls, ptr @str, ptr @str.1)
+Call parameter type does not match function signature!
+i64 undef
+ ptr  call void %jni.callfn(i64 undef, ptr %load, ptr %jni.mid)