diff --git a/core/city-hash.cpp b/core/city-hash.cpp
index 7b9790a..b8a7791 100644
--- a/core/city-hash.cpp
+++ b/core/city-hash.cpp
@@ -505,6 +505,16 @@
       CityHash128WithSeed(s, len, uint128(k0, k1));
 }
 
+// NFD NOTE
+// The following code block is commented out due to the following reasons.
+// - It requires the "citycrc.h" header file, which is not included in the
+//   NFD code base.
+// - The functions defined below are not used by the current NFD
+//   implementation.
+// The header file "citycrc.h" is available at
+// https://code.google.com/p/cityhash/source/browse/trunk/src/citycrc.h
+
+/*
 #ifdef __SSE4_2__
 #include <citycrc.h>
 #include <nmmintrin.h>
@@ -637,3 +647,4 @@
 }
 
 #endif
+*/