diff --git a/sys/dev/uart/uart_cpu_arm64.c b/sys/dev/uart/uart_cpu_arm64.c
--- a/sys/dev/uart/uart_cpu_arm64.c
+++ b/sys/dev/uart/uart_cpu_arm64.c
@@ -94,18 +94,28 @@
 	if (err == 0)
 		return (0);
 
+	err = ENXIO;
 #ifdef DEV_ACPI
 	/* Check if SPCR can tell us what console to use. */
 	if (uart_cpu_acpi_spcr(devtype, di) == 0)
 		return (0);
-#endif
-	err = ENXIO;
+#ifndef FDT
+	/*
+	 * In an ideal world, we'd just fall through and bail out because FDT
+	 * isn't defined, thus `err` doesn't get reassigned and we immediately
+	 * return.  As of clang 14, later uses of `shift`, et al., raise
+	 *  warnings because it can't deduce that we're about to return.
+	 */
+	else
+		return (ENXIO);
+#endif /* !FDT */
+#endif /* DEV_ACPI */
 #ifdef FDT
 	if (err != 0) {
 		err = uart_cpu_fdt_probe(&class, &bst, &bsh, &br, &rclk,
 		    &shift, &iowidth, devtype);
 	}
-#endif
+#endif /* FDT */
 	if (err != 0)
 		return (err);