diff --git a/src/hostapi/asio/iasiothiscallresolver.cpp b/src/hostapi/asio/iasiothiscallresolver.cpp
index 8dfefbd..28f26df 100644
--- a/src/hostapi/asio/iasiothiscallresolver.cpp
+++ b/src/hostapi/asio/iasiothiscallresolver.cpp
@@ -156,7 +156,7 @@
 // We only need IASIOThiscallResolver at all if we are on Win32. For other
 // platforms we simply bypass the IASIOThiscallResolver definition to allow us
 // to be safely #include'd whatever the platform to keep client code portable
-#if defined(WIN32) || defined(_WIN32) || defined(__WIN32__)
+#if (defined(WIN32) || defined(_WIN32) || defined(__WIN32__)) && !defined(_WIN64)
 
 
 // If microsoft compiler we can call IASIO directly so IASIOThiscallResolver
diff --git a/src/hostapi/asio/iasiothiscallresolver.h b/src/hostapi/asio/iasiothiscallresolver.h
index 2ecfed7..21d53b3 100644
--- a/src/hostapi/asio/iasiothiscallresolver.h
+++ b/src/hostapi/asio/iasiothiscallresolver.h
@@ -111,7 +111,7 @@
 // We only need IASIOThiscallResolver at all if we are on Win32. For other
 // platforms we simply bypass the IASIOThiscallResolver definition to allow us
 // to be safely #include'd whatever the platform to keep client code portable
-#if defined(WIN32) || defined(_WIN32) || defined(__WIN32__)
+#if (defined(WIN32) || defined(_WIN32) || defined(__WIN32__)) && !defined(_WIN64)
 
 
 // If microsoft compiler we can call IASIO directly so IASIOThiscallResolver