diff --git a/lib/asyn-thrdd.c b/lib/asyn-thrdd.c
index dbc13d0722..5b451ac65e 100644
--- a/lib/asyn-thrdd.c
+++ b/lib/asyn-thrdd.c
@@ -135,6 +135,13 @@ static void addr_ctx_unlink(struct async_thrdd_addr_ctx **paddr_ctx,
 #ifndef CURL_DISABLE_SOCKETPAIR
   if(!destroy) {
     if(!data) { /* Called from thread, transfer still waiting on results. */
+      /* Mark thread as done and signal the condition again, in case the
+       * one waiting missed our fist signal at the start. */
+      addr_ctx->thrd_done = TRUE;
+#ifdef USE_CURL_COND_T
+      Curl_cond_signal(&addr_ctx->cond);
+#endif
+
       if(addr_ctx->sock_pair[1] != CURL_SOCKET_BAD) {
 #ifdef USE_EVENTFD
         const uint64_t buf[1] = { 1 };
@@ -379,7 +386,7 @@ static void async_thrdd_destroy(struct Curl_easy *data)
     bool done = TRUE;
 
     Curl_mutex_acquire(&addr->mutx);
-    done = (addr->ref_count <= 1);
+    done = addr->thrd_done;
     Curl_mutex_release(&addr->mutx);
     if(done) {
       Curl_thread_join(&addr->thread_hnd);
@@ -504,9 +511,13 @@ static bool async_thrdd_init(struct Curl_easy *data,
   }
   else {
 #ifdef USE_CURL_COND_T
-    /* need to handshake with thread for participation in ref counting */
-    Curl_cond_wait(&addr_ctx->cond, &addr_ctx->mutx);
-    DEBUGASSERT(addr_ctx->ref_count >= 1);
+    /* need to handshake with thread for participation in ref counting.
+     * We wait to see the thread having incremented `ref_count`, so it
+     * started. However it may run to its end before we get the
+     * signal, in which case `ref_count` is 1 again, but then
+     * `thrd_done` is TRUE.*/
+    while((addr_ctx->ref_count <= 1) && !addr_ctx->thrd_done)
+      Curl_cond_wait(&addr_ctx->cond, &addr_ctx->mutx);
 #endif
     Curl_mutex_release(&addr_ctx->mutx);
   }
@@ -537,7 +548,7 @@ static void async_thrdd_shutdown(struct Curl_easy *data)
     return;
 
   Curl_mutex_acquire(&addr_ctx->mutx);
-  done = (addr_ctx->ref_count <= 1);
+  done = addr_ctx->thrd_done;
   /* We are no longer interested in wakeups */
   if(addr_ctx->sock_pair[1] != CURL_SOCKET_BAD) {
     wakeup_close(addr_ctx->sock_pair[1]);
@@ -660,7 +671,7 @@ CURLcode Curl_async_is_resolved(struct Curl_easy *data,
     return CURLE_FAILED_INIT;
 
   Curl_mutex_acquire(&thrdd->addr->mutx);
-  done = (thrdd->addr->ref_count == 1);
+  done = thrdd->addr->thrd_done;
   Curl_mutex_release(&thrdd->addr->mutx);
 
   if(done) {
diff --git a/lib/asyn.h b/lib/asyn.h
index 5e56532bf0..58c09e98e3 100644
--- a/lib/asyn.h
+++ b/lib/asyn.h
@@ -196,6 +196,7 @@ struct async_thrdd_addr_ctx {
   int port;
   int sock_error;
   int ref_count;
+  BIT(thrd_done);
 };
 
 /* Context for threaded resolver */