diff --git a/pureboot/pureboot.cpp b/pureboot/pureboot.cpp
index 96671df..c2f154c 100644
--- a/pureboot/pureboot.cpp
+++ b/pureboot/pureboot.cpp
@@ -177,7 +177,15 @@ struct hardware_link {
 	// bit-addressable I/O (the classic megas), lds + skip (4) in extended
 	// I/O. A uint32_t countdown pays one more sbci — window_polls() adds it
 	// where the count forces the wide type. Held by the pureboot.window gate.
-	static constexpr std::uint8_t poll_cycles = avr::hw::usart_of<usart_unit>::ucsra::addr < 0x40 ? 7 : 9;
+	// The lookup rides the baud parameter so it stays dependent: the trait is
+	// an incomplete type on the USART-less chips, which parse this template
+	// without ever instantiating it.
+	template <avr::baud_t Baud, typename U = avr::hw::usart_of<usart_unit>>
+	static consteval std::uint8_t poll_cost()
+	{
+		return U::ucsra::addr < 0x40 ? 7 : 9;
+	}
+	static constexpr std::uint8_t poll_cycles = poll_cost<B>();
 
 	static void init()
 	{