diff --git a/examples/177-generic-into-block.sx b/examples/177-generic-into-block.sx
new file mode 100644
index 0000000..8344a29
--- /dev/null
+++ b/examples/177-generic-into-block.sx
@@ -0,0 +1,37 @@
+// FFI plan step 5.2 — generic `Into(Block) for Closure(..$args) ->
+// $R` impl. One impl in stdlib covers every closure shape; the
+// compiler monomorphises the impl body per call shape and emits a
+// dedicated `__invoke` `callconv(.c)` trampoline + Block literal
+// (via `#insert build_block_convert($args, $R);`).
+//
+// This test exercises a closure shape (`Closure(s64, s64) -> void`)
+// that has NO hand-rolled `Into(Block)` impl in
+// `library/modules/std/objc_block.sx`. Before step 5.2 lands,
+// `xx cl : Block` errors out with the "no Into(Block) for
+// cl_s64_s64__void" focused diagnostic. After the generic impl
+// lands, the same call resolves through the pack-shaped impl and
+// the per-shape trampoline ferries control back to the sx closure.
+//
+// The block is invoked directly through `b.invoke` (a typed
+// `callconv(.c)` fn-pointer) — the same shape the Apple Block
+// runtime calls when a UIKit/Foundation API hands the block back
+// to its registered invoke.
+
+#import "modules/std.sx";
+#import "modules/std/objc_block.sx";
+
+g_a: s64 = 0;
+g_b: s64 = 0;
+
+main :: () -> s32 {
+    cl := (a: s64, b: s64) => { g_a = a; g_b = b; };
+    blk : Block = xx cl;
+
+    invoke_fn : (*Block, s64, s64) -> void callconv(.c) = xx blk.invoke;
+    invoke_fn(@blk, 10, 20);
+
+    if g_a != 10 { print("FAIL: g_a={}\n", g_a); return 1; }
+    if g_b != 20 { print("FAIL: g_b={}\n", g_b); return 1; }
+    print("generic-into-block ok: a={} b={}\n", g_a, g_b);
+    0;
+}
diff --git a/tests/expected/177-generic-into-block.exit b/tests/expected/177-generic-into-block.exit
new file mode 100644
index 0000000..573541a
--- /dev/null
+++ b/tests/expected/177-generic-into-block.exit
@@ -0,0 +1 @@
+0
diff --git a/tests/expected/177-generic-into-block.txt b/tests/expected/177-generic-into-block.txt
new file mode 100644
index 0000000..7658721
--- /dev/null
+++ b/tests/expected/177-generic-into-block.txt
@@ -0,0 +1 @@
+generic-into-block ok: a=10 b=20