diff --git a/src/file_reader.cpp b/src/file_reader.cpp
index 0efaeaef..1d7a6f7f 100644
--- a/src/file_reader.cpp
+++ b/src/file_reader.cpp
@@ -143,7 +143,7 @@ class MMapException : std::exception {};
 char*
 mmapReadOnly(int fd, offset_type offset, size_type size)
 {
-#if defined(__APPLE__) || defined(__OpenBSD__) || defined(__HAIKU__)
+#if defined(__APPLE__) || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__HAIKU__)
   const auto MAP_FLAGS = MAP_PRIVATE;
 #elif defined(__FreeBSD__)
   const auto MAP_FLAGS = MAP_PRIVATE|MAP_PREFAULT_READ;