diff --git a/src/core/thread/lowpan.hpp b/src/core/thread/lowpan.hpp
index 9f359587a..f5ef85e90 100644
--- a/src/core/thread/lowpan.hpp
+++ b/src/core/thread/lowpan.hpp
@@ -391,6 +391,12 @@ OT_TOOL_PACKED_BEGIN
 class FragmentHeader
 {
 public:
+    /**
+     * This constructor initializes the Fragment Header.
+     *
+     */
+    FragmentHeader(void) { mDispatchSize = HostSwap16(kDispatch); mTag = 0; mOffset = 0; }
+
     /**
      * This method initializes the Fragment Header.
      *