diff --git a/src/thread.c b/src/thread.c
index 0ec191cc4..c1a6d6ad8 100644
--- a/src/thread.c
+++ b/src/thread.c
@@ -193,6 +193,9 @@ SEXP rnng_messenger_thread_create(SEXP args) {
 
 // threaded functions ----------------------------------------------------------
 
+// # nocov start
+// tested interactively
+
 static void thread_aio_finalizer(SEXP xptr) {
 
   if (NANO_PTR(xptr) == NULL) return;
@@ -209,6 +212,82 @@ static void thread_aio_finalizer(SEXP xptr) {
 
 }
 
+
+static void rnng_wait_thread_single(void *args) {
+
+  nano_thread_aio *taio = (nano_thread_aio *) args;
+  nano_cv *ncv = taio->cv;
+  nng_mtx *mtx = ncv->mtx;
+  nng_cv *cv = ncv->cv;
+
+  nng_aio_wait(taio->aio);
+
+  nng_mtx_lock(mtx);
+  ncv->condition = 1;
+  nng_cv_wake(cv);
+  nng_mtx_unlock(mtx);
+
+}
+
+void single_wait_thread_create(SEXP x) {
+
+  nano_aio *aiop = (nano_aio *) NANO_PTR(x);
+  nano_thread_aio *taio = R_Calloc(1, nano_thread_aio);
+  nano_cv *ncv = R_Calloc(1, nano_cv);
+  taio->aio = aiop->aio;
+  taio->cv = ncv;
+  nng_mtx *mtx;
+  nng_cv *cv;
+  int xc, signalled;
+
+  if ((xc = nng_mtx_alloc(&mtx)))
+    goto exitlevel1;
+
+  if ((xc = nng_cv_alloc(&cv, mtx)))
+    goto exitlevel2;
+
+  ncv->mtx = mtx;
+  ncv->cv = cv;
+
+  if ((xc = nng_thread_create(&taio->thr, rnng_wait_thread_single, taio)))
+    goto exitlevel3;
+
+  SEXP xptr;
+  PROTECT(xptr = R_MakeExternalPtr(taio, R_NilValue, R_NilValue));
+  R_RegisterCFinalizerEx(xptr, thread_aio_finalizer, TRUE);
+  R_MakeWeakRef(x, xptr, R_NilValue, TRUE);
+  UNPROTECT(1);
+
+  nng_time time = nng_clock();
+
+  while (1) {
+    time = time + 400;
+    signalled = 1;
+    nng_mtx_lock(mtx);
+    while (ncv->condition == 0) {
+      if (nng_cv_until(cv, time) == NNG_ETIMEDOUT) {
+        signalled = 0;
+        break;
+      }
+    }
+    nng_mtx_unlock(mtx);
+    if (signalled) break;
+    R_CheckUserInterrupt();
+  }
+
+  return;
+
+  exitlevel3:
+  nng_cv_free(cv);
+  exitlevel2:
+  nng_mtx_free(mtx);
+  exitlevel1:
+  ERROR_OUT(xc);
+
+}
+
+// # nocov end
+
 static void thread_duo_finalizer(SEXP xptr) {
 
   if (NANO_PTR(xptr) == NULL) return;
@@ -286,79 +365,6 @@ static void rnng_wait_thread(void *args) {
 
 }
 
-static void rnng_wait_thread_single(void *args) {
-
-  nano_thread_aio *taio = (nano_thread_aio *) args;
-  nano_cv *ncv = taio->cv;
-  nng_mtx *mtx = ncv->mtx;
-  nng_cv *cv = ncv->cv;
-
-  nng_aio_wait(taio->aio);
-
-  nng_mtx_lock(mtx);
-  ncv->condition = 1;
-  nng_cv_wake(cv);
-  nng_mtx_unlock(mtx);
-
-}
-
-void single_wait_thread_create(SEXP x) {
-
-  nano_aio *aiop = (nano_aio *) NANO_PTR(x);
-  nano_thread_aio *taio = R_Calloc(1, nano_thread_aio);
-  nano_cv *ncv = R_Calloc(1, nano_cv);
-  taio->aio = aiop->aio;
-  taio->cv = ncv;
-  nng_mtx *mtx;
-  nng_cv *cv;
-  int xc, signalled;
-
-  if ((xc = nng_mtx_alloc(&mtx)))
-    goto exitlevel1;
-
-  if ((xc = nng_cv_alloc(&cv, mtx)))
-    goto exitlevel2;
-
-  ncv->mtx = mtx;
-  ncv->cv = cv;
-
-  if ((xc = nng_thread_create(&taio->thr, rnng_wait_thread_single, taio)))
-    goto exitlevel3;
-
-  SEXP xptr;
-  PROTECT(xptr = R_MakeExternalPtr(taio, R_NilValue, R_NilValue));
-  R_RegisterCFinalizerEx(xptr, thread_aio_finalizer, TRUE);
-  R_MakeWeakRef(x, xptr, R_NilValue, TRUE);
-  UNPROTECT(1);
-
-  nng_time time = nng_clock();
-
-  while (1) {
-    time = time + 400;
-    signalled = 1;
-    nng_mtx_lock(mtx);
-    while (ncv->condition == 0) {
-      if (nng_cv_until(cv, time) == NNG_ETIMEDOUT) {
-        signalled = 0;
-        break;
-      }
-    }
-    nng_mtx_unlock(mtx);
-    if (signalled) break;
-    R_CheckUserInterrupt();
-  }
-
-  return;
-
-  exitlevel3:
-  nng_cv_free(cv);
-  exitlevel2:
-  nng_mtx_free(mtx);
-  exitlevel1:
-  ERROR_OUT(xc);
-
-}
-
 SEXP rnng_wait_thread_create(SEXP x) {
 
   const SEXPTYPE typ = TYPEOF(x);