diff --git a/third-party/libnatpmp/Makefile.am b/third-party/libnatpmp/Makefile.am
index 5e268e1b5..3fca7d53c 100644
--- a/third-party/libnatpmp/Makefile.am
+++ b/third-party/libnatpmp/Makefile.am
@@ -5,6 +5,7 @@ libnatpmp_a_SOURCES = \
     natpmp.c
 
 noinst_HEADERS = \
+    declspec.h \
     getgateway.h \
     natpmp.h
 
diff --git a/third-party/libnatpmp/declspec.h b/third-party/libnatpmp/declspec.h
new file mode 100644
index 000000000..ea479d1e6
--- /dev/null
+++ b/third-party/libnatpmp/declspec.h
@@ -0,0 +1,15 @@
+#ifndef __DECLSPEC_H__
+#define __DECLSPEC_H__
+
+#if defined(WIN32) && !defined(STATICLIB)
+	#ifdef NATPMP_EXPORTS
+		#define LIBSPEC __declspec(dllexport)
+	#else
+		#define LIBSPEC __declspec(dllimport)
+	#endif
+#else
+	#define LIBSPEC
+#endif
+
+#endif
+