diff --git a/winpr/include/winpr/spec.h b/winpr/include/winpr/spec.h
index bcd42b1c0..9dbf394db 100644
--- a/winpr/include/winpr/spec.h
+++ b/winpr/include/winpr/spec.h
@@ -73,6 +73,24 @@
 #endif
 #endif
 
+#if defined(_WIN32) || defined(__CYGWIN__)
+  #ifdef __GNUC__
+    #define DECLSPEC_EXPORT __attribute__((dllexport))
+    #define DECLSPEC_IMPORT __attribute__((dllimport))
+  #else
+    #define DECLSPEC_EXPORT __declspec(dllexport)
+    #define DECLSPEC_IMPORT __declspec(dllimport)
+  #endif
+#else
+  #if defined(__GNUC__) && __GNUC__ >= 4
+    #define DECLSPEC_EXPORT __attribute__ ((visibility("default")))
+    #define DECLSPEC_IMPORT
+  #else
+    #define DECLSPEC_EXPORT
+    #define DECLSPEC_IMPORT
+  #endif
+#endif
+
 #ifndef DECLSPEC_NORETURN
 #if (defined(__GNUC__) || defined(_MSC_VER) || defined(__clang__))
 #define DECLSPEC_NORETURN __declspec(noreturn)
diff --git a/winpr/include/winpr/wtypes.h b/winpr/include/winpr/wtypes.h
index be617ec72..26299ed3d 100644
--- a/winpr/include/winpr/wtypes.h
+++ b/winpr/include/winpr/wtypes.h
@@ -39,6 +39,7 @@
 #ifndef _WIN32
 
 #define WINAPI
+#define CDECL
 
 #define __int8	char
 #define __int16 short