diff --git a/src/core/pluginloader.c b/src/core/pluginloader.c
index c0fef87..cb0b016 100644
--- a/src/core/pluginloader.c
+++ b/src/core/pluginloader.c
@@ -44,7 +44,7 @@ struct uhub_plugin* plugin_open(const char* filename)
 #ifdef HAVE_DLOPEN
 		LOG_ERROR("Unable to open plugin %s: %s", filename, dlerror());
 #else
-		LOG_ERROR("Unable to open plugin %s: %s", filename, GetLastError());
+		LOG_ERROR("Unable to open plugin %s: %d", filename, GetLastError());
 #endif
 		hub_free(plugin);
 		return 0;
diff --git a/src/plugin_api/handle.h b/src/plugin_api/handle.h
index 9096cae..991d463 100644
--- a/src/plugin_api/handle.h
+++ b/src/plugin_api/handle.h
@@ -193,12 +193,12 @@ struct plugin_handle
  * @param config A configuration string
  * @return 0 on success, -1 on error.
  */
-extern int plugin_register(struct plugin_handle* handle, const char* config);
+PLUGIN_API int plugin_register(struct plugin_handle* handle, const char* config);
 
 /**
  * @return 0 on success, -1 on error.
  */
-extern int plugin_unregister(struct plugin_handle*);
+PLUGIN_API int plugin_unregister(struct plugin_handle*);
 
 typedef int (*plugin_register_f)(struct plugin_handle* handle, const char* config);
 typedef int (*plugin_unregister_f)(struct plugin_handle*);
diff --git a/src/plugins/mod_auth_simple.c b/src/plugins/mod_auth_simple.c
index f5b712d..7af92f9 100644
--- a/src/plugins/mod_auth_simple.c
+++ b/src/plugins/mod_auth_simple.c
@@ -203,7 +203,7 @@ static plugin_st delete_user(struct plugin_handle* plugin, struct auth_info* use
 	return st_default;
 }
 
-int plugin_register(struct plugin_handle* plugin, const char* config)
+PLUGIN_API int plugin_register(struct plugin_handle* plugin, const char* config)
 {
 	PLUGIN_INITIALIZE(plugin, "File authentication plugin", "0.1", "Authenticate users based on a read-only text file.");
 
@@ -219,7 +219,7 @@ int plugin_register(struct plugin_handle* plugin, const char* config)
 	return -1;
 }
 
-int plugin_unregister(struct plugin_handle* plugin)
+PLUGIN_API int plugin_unregister(struct plugin_handle* plugin)
 {
 	set_error_message(plugin, 0);
 	unload_acl(plugin->ptr);
diff --git a/src/system.h b/src/system.h
index a909fd0..3078460 100644
--- a/src/system.h
+++ b/src/system.h
@@ -256,4 +256,9 @@ typedef unsigned __int64 uint64_t;
 #define NEED_GETOPT
 #endif
 
+#if defined(__CYGWIN__) || defined(__MINGW32__) || defined(_MSC_VER)
+#define PLUGIN_API __declspec(dllexport)
+#else
+#define PLUGIN_API
+#endif
 #endif /* HAVE_UHUB_SYSTEM_H */