diff --git a/include/boost/smart_ptr/detail/sp_interlocked.hpp b/include/boost/smart_ptr/detail/sp_interlocked.hpp
index 79cae14..68ce292 100644
--- a/include/boost/smart_ptr/detail/sp_interlocked.hpp
+++ b/include/boost/smart_ptr/detail/sp_interlocked.hpp
@@ -32,6 +32,11 @@
 // MinGW-w64 provides intrin.h for both 32 and 64-bit targets.
 # define BOOST_SP_HAS_INTRIN_H
 
+#elif defined( __LP64__ )
+
+// We have to use intrin.h on Cygwin 64
+# define BOOST_SP_HAS_INTRIN_H
+
 // Intel C++ on Windows on VC10+ stdlib
 #elif defined( BOOST_INTEL_WIN ) && defined( _CPPLIB_VER ) && _CPPLIB_VER >= 520
 
diff --git a/test/sp_interlocked_test.cpp b/test/sp_interlocked_test.cpp
index 1b075b4..73a57f6 100644
--- a/test/sp_interlocked_test.cpp
+++ b/test/sp_interlocked_test.cpp
@@ -13,9 +13,20 @@
 #include <boost/smart_ptr/detail/sp_interlocked.hpp>
 #include <boost/detail/lightweight_test.hpp>
 
+#ifndef __LP64__
+
+typedef long long_type;
+
+#else
+
+// On Cygwin 64, long is 64 bit
+typedef int long_type;
+
+#endif
+
 int main()
 {
-    long x = 0, r;
+    long_type x = 0, r;
 
     r = BOOST_SP_INTERLOCKED_INCREMENT( &x );