diff --git a/selection.c b/selection.c
index 8ed0b6da..2839636a 100644
--- a/selection.c
+++ b/selection.c
@@ -384,13 +384,14 @@ send(void *data, struct wl_data_source *wl_data_source, const char *mime_type,
         return;
     }
 
-    switch (async_write(fd, selection, len, &(size_t){0})) {
+    size_t async_idx = 0;
+    switch (async_write(fd, selection, len, &async_idx)) {
     case ASYNC_WRITE_REMAIN: {
         struct clipboard_send *ctx = malloc(sizeof(*ctx));
         *ctx = (struct clipboard_send) {
             .data = strdup(selection),
             .len = len,
-            .idx = 0,
+            .idx = async_idx,
         };
 
         if (fdm_add(wayl->fdm, fd, EPOLLOUT, &fdm_send, ctx))
@@ -475,13 +476,14 @@ primary_send(void *data,
         return;
     }
 
-    switch (async_write(fd, selection, len, &(size_t){0})) {
+    size_t async_idx = 0;
+    switch (async_write(fd, selection, len, &async_idx)) {
     case ASYNC_WRITE_REMAIN: {
         struct clipboard_send *ctx = malloc(sizeof(*ctx));
         *ctx = (struct clipboard_send) {
             .data = strdup(selection),
             .len = len,
-            .idx = 0,
+            .idx = async_idx,
         };
 
         if (fdm_add(wayl->fdm, fd, EPOLLOUT, &fdm_send, ctx))
diff --git a/terminal.c b/terminal.c
index 887e90c1..0cfbdb2e 100644
--- a/terminal.c
+++ b/terminal.c
@@ -32,6 +32,7 @@
 bool
 term_to_slave(struct terminal *term, const void *_data, size_t len)
 {
+    size_t async_idx = 0;
     if (tll_length(term->ptmx_buffer) > 0) {
         /* With a non-empty queue, EPOLLOUT has already been enabled */
         goto enqueue_data;
@@ -42,7 +43,7 @@ term_to_slave(struct terminal *term, const void *_data, size_t len)
      * switch to asynchronous.
      */
 
-    switch (async_write(term->ptmx, _data, len, &(size_t){0})) {
+    switch (async_write(term->ptmx, _data, len, &async_idx)) {
     case ASYNC_WRITE_REMAIN:
         /* Switch to asynchronous mode; let FDM write the remaining data */
         if (!fdm_event_add(term->fdm, term->ptmx, EPOLLOUT))
@@ -73,7 +74,7 @@ enqueue_data:
         struct ptmx_buffer queued = {
             .data = copy,
             .len = len,
-            .idx = 0,
+            .idx = async_idx,
         };
         tll_push_back(term->ptmx_buffer, queued);
     }