diff --git a/sys/arm/arm/busdma_machdep.c b/sys/arm/arm/busdma_machdep.c
index a754cb13ddc..ccf593b11aa 100644
--- a/sys/arm/arm/busdma_machdep.c
+++ b/sys/arm/arm/busdma_machdep.c
@@ -535,11 +535,12 @@ bus_dma_tag_set_domain(bus_dma_tag_t dmat, int domain)
 int
 bus_dma_tag_destroy(bus_dma_tag_t dmat)
 {
-	bus_dma_tag_t dmat_copy;
+#ifdef KTR
+	bus_dma_tag_t dmat_copy = dmat;
+#endif
 	int error;
 
 	error = 0;
-	dmat_copy = dmat;
 
 	if (dmat != NULL) {
 		if (dmat->map_count != 0) {