diff --git a/lib/filesys.cpp b/lib/filesys.cpp
index a16c46a051..6535a80433 100644
--- a/lib/filesys.cpp
+++ b/lib/filesys.cpp
@@ -505,6 +505,7 @@ FILE* boinc_fopen(const char* path, const char* mode) {
     }
     if (f) {
         if (-1 == fcntl(fileno(f), F_SETFD, FD_CLOEXEC)) {
+            fclose(f);
             return 0;
         }
     }