diff --git a/em.c b/em.c
index 1c4b8eb..5605e01 100644
--- a/em.c
+++ b/em.c
@@ -4410,6 +4410,7 @@ int main (int argc, char **argv) {
       printf("Open returned %d redirecting stderr\n", templ);
     exit(1);
   }
+  setvbuf(stderr, NULL, _IONBF, 0);
 
   /* initialize global variables */