diff --git a/lib/memdebug.c b/lib/memdebug.c
index 110169474bc652e2b2e7b081bc8af93a051133e5..582387cf9ceb533df658ea090025164f1bae0573 100644
--- a/lib/memdebug.c
+++ b/lib/memdebug.c
@@ -73,6 +73,10 @@ void curl_memdebug(const char *logname)
       logfile = fopen(logname, "w");
     else
       logfile = stderr;
+#ifdef MEMDEBUG_LOG_SYNC
+    /* Flush the log file after every line so the log isn't lost in a crash */
+    setvbuf(logfile, (char *)NULL, _IOLBF, 0);
+#endif
   }
 }