diff --git a/src/htx.c b/src/htx.c
index c29a66d..cd21050 100644
--- a/src/htx.c
+++ b/src/htx.c
@@ -252,11 +252,13 @@
 			ret = 1;
 		}
 		else if ((sz + delta) < headroom) {
+			uint32_t oldaddr = blk->addr;
+
 			/* Move the block's payload into the headroom */
 			blk->addr = htx->head_addr;
 			htx->tail_addr -= sz;
 			htx->head_addr += sz + delta;
-			if (blk->addr == htx->end_addr) {
+			if (oldaddr == htx->end_addr) {
 				if (htx->end_addr == htx->tail_addr) {
 					htx->tail_addr = htx->head_addr;
 					htx->head_addr = htx->end_addr = 0;