diff --git a/src/testlo.c b/src/testlo.c
index 2d6be38..415d349 100644
--- a/src/testlo.c
+++ b/src/testlo.c
@@ -60,6 +60,7 @@
 
 #define TEST(cond) if (!(cond)) { fprintf(stderr, "FAILED " #cond \
                       " at %s:%d\n", __FILE__, __LINE__); \
+                  fflush(stderr); \
                   exit(1); } \
            else { printf("passed " #cond "\n"); }