diff --git a/tools/bt.cpp b/tools/bt.cpp
index eeac686..7f88517 100644
--- a/tools/bt.cpp
+++ b/tools/bt.cpp
@@ -21,6 +21,7 @@
     if (fileSize == 0)
     {
         std::fprintf(stderr, "Zero-length file, or other file access error\n");
+        sys->close(inputFd);
         return false;
     }