diff --git a/src/interfaces/ecpg/ecpglib/misc.c b/src/interfaces/ecpg/ecpglib/misc.c
index a07d0dfb9f..1feb5c03e1 100644
--- a/src/interfaces/ecpg/ecpglib/misc.c
+++ b/src/interfaces/ecpg/ecpglib/misc.c
@@ -477,8 +477,8 @@ win32_pthread_once(volatile pthread_once_t *once, void (*fn) (void))
 		pthread_mutex_lock(&win32_pthread_once_lock);
 		if (!*once)
 		{
-			*once = true;
 			fn();
+			*once = true;
 		}
 		pthread_mutex_unlock(&win32_pthread_once_lock);
 	}