diff --git a/bench/async_bench.cpp b/bench/async_bench.cpp
index 802a07cb..8d1e0edc 100644
--- a/bench/async_bench.cpp
+++ b/bench/async_bench.cpp
@@ -35,6 +35,7 @@ int count_lines(const char *filename)
         if ('\n' == ch)
             counter++;
     }
+    fclose(infile);
 
     return counter;
 }