diff --git a/src/uniproc_win64.c b/src/uniproc_win64.c
index e805893..eadba5b 100644
--- a/src/uniproc_win64.c
+++ b/src/uniproc_win64.c
@@ -158,7 +158,7 @@ void uniproc_await_processes(const uniproc_process* p, int* return_codes, const
 		h[i] = (HANDLE)p[i]._proc_hdl;
 		num_valid_handles++;
 	}
-
+	if (num_valid_handles == 0) return;
 	WaitForMultipleObjects(num_valid_handles, h, 1, INFINITE);
 	free(h);
 
@@ -191,6 +191,7 @@ int uniproc_are_processes_finished(const uniproc_process* p, const size_t num_pr
 		h[i] = (HANDLE)p[i]._proc_hdl;
 		num_valid_handles++;
 	}
+	if (num_valid_handles == 0) return true;
 	DWORD ret = WaitForMultipleObjects(num_valid_handles, h, 1, 0);
 	free(h);
 	return ret >= WAIT_OBJECT_0 && ret < WAIT_OBJECT_0 + num_valid_handles;
@@ -212,6 +213,7 @@ void uniproc_await_any_processes(const uniproc_process* p, const size_t num_proc
 		h[i] = (HANDLE)p[i]._proc_hdl;
 		num_valid_handles++;
 	}
+	if (num_valid_handles == 0) return;
 	WaitForMultipleObjects(num_valid_handles, h, 0, INFINITE);
 	free(h);
 }