diff --git a/CMakeLists.txt b/CMakeLists.txt
index 92fbf476..c8ff6072 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -64,9 +64,10 @@ include_directories(
   ${CMAKE_CURRENT_BINARY_DIR}
   )
 
-# Platform
+# Target Platform
 if (WIN32 OR MINGW OR MSYS OR CYGWIN)
   set(HOSTOS "windows")
+  set(GETDNS_ON_WINDOWS 1)
 elseif (APPLE)
   set(HOSTOS "macos")
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -D_DARWIN_C_SOURCE")
@@ -126,6 +127,7 @@ check_include_file(stdio.h HAVE_STDIO_H)
 check_include_file(stdlib.h HAVE_STDLIB_H)
 check_include_file(string.h HAVE_STRING_H)
 check_include_file(time.h HAVE_TIME_H)
+check_include_file(unistd.h HAVE_UNISTD_H)
 
 check_include_file(signal.h HAVE_SIGNAL_H)
 check_include_file(sys/poll.h HAVE_SYS_POLL_H)
diff --git a/cmake/include/cmakeconfig.h.in b/cmake/include/cmakeconfig.h.in
index 578b5495..ede085aa 100644
--- a/cmake/include/cmakeconfig.h.in
+++ b/cmake/include/cmakeconfig.h.in
@@ -41,6 +41,7 @@
 #cmakedefine HAVE_WINSOCK_H     1
 #cmakedefine HAVE_WINSOCK2_H    1
 #cmakedefine HAVE_WS2TCPIP_H    1
+#cmakedefine GETDNS_ON_WINDOWS  1
 
 #cmakedefine HAVE_SSL           1
 
@@ -151,11 +152,25 @@
 # define PRIsz "zu"
 #endif
 
+#ifdef HAVE_STDINT_H
 #include <stdint.h>
+#endif
+
+#ifdef HAVE_STDIO_H
 #include <stdio.h>
+#endif
+
+#ifdef HAVE_UNISTD_H
 #include <unistd.h>
+#endif
+
+#ifdef HAVE_ASSERT_H
 #include <assert.h>
+#endif
+
+#ifdef HAVE_STRING_H
 #include <string.h>
+#endif
 
 #ifdef __cplusplus
 extern "C" {