diff --git a/src/Backends/Platform/Null.cpp b/src/Backends/Platform/Null.cpp
index b64360f8..d3c0076e 100644
--- a/src/Backends/Platform/Null.cpp
+++ b/src/Backends/Platform/Null.cpp
@@ -4,8 +4,11 @@
 
 #include "../../Attributes.h"
 
-bool Backend_Init(void)
+bool Backend_Init(void (*drag_and_drop_callback)(const char *path), void (*window_focus_callback)(bool focus));
 {
+	(void)drag_and_drop_callback;
+	(void)window_focus_callback;
+
 	return true;
 }
 
diff --git a/src/Backends/Platform/WiiU.cpp b/src/Backends/Platform/WiiU.cpp
index db2aeb0b..c8903cb6 100644
--- a/src/Backends/Platform/WiiU.cpp
+++ b/src/Backends/Platform/WiiU.cpp
@@ -16,8 +16,11 @@
 
 static unsigned long ticks_per_second;
 
-bool Backend_Init(void)
+bool Backend_Init(void (*drag_and_drop_callback)(const char *path), void (*window_focus_callback)(bool focus));
 {
+	(void)drag_and_drop_callback;
+	(void)window_focus_callback;
+
 	WHBProcInit();
 
 	if (!WHBMountSdCard())