diff --git a/Userland/Libraries/LibC/wchar.cpp b/Userland/Libraries/LibC/wchar.cpp
index 4bdc43545a..af9de8049b 100644
--- a/Userland/Libraries/LibC/wchar.cpp
+++ b/Userland/Libraries/LibC/wchar.cpp
@@ -417,4 +417,10 @@ wchar_t* wmemmove(wchar_t* dest, const wchar_t* src, size_t n)
 
     return dest;
 }
+
+unsigned long wcstoul(const wchar_t*, wchar_t**, int)
+{
+    dbgln("TODO: Implement wcstoul()");
+    TODO();
+}
 }
diff --git a/Userland/Libraries/LibC/wchar.h b/Userland/Libraries/LibC/wchar.h
index 8eea8e919e..a79f2d61fc 100644
--- a/Userland/Libraries/LibC/wchar.h
+++ b/Userland/Libraries/LibC/wchar.h
@@ -47,5 +47,6 @@ wchar_t* wmemchr(const wchar_t*, wchar_t, size_t);
 wchar_t* wmemcpy(wchar_t*, const wchar_t*, size_t);
 wchar_t* wmemset(wchar_t*, wchar_t, size_t);
 wchar_t* wmemmove(wchar_t*, const wchar_t*, size_t);
+unsigned long wcstoul(const wchar_t*, wchar_t**, int);
 
 __END_DECLS