diff --git a/library/DataDefs.cpp b/library/DataDefs.cpp
index 2de8c156e..1c77f02d6 100644
--- a/library/DataDefs.cpp
+++ b/library/DataDefs.cpp
@@ -55,7 +55,7 @@ virtual_identity::virtual_identity(const char *dfhack_name, const char *original
 static tthread::mutex *known_mutex = NULL;
 std::map<void*, virtual_identity*> virtual_identity::known;
 
-virtual_identity *virtual_identity::get(virtual_class *instance_ptr)
+virtual_identity *virtual_identity::get(virtual_ptr instance_ptr)
 {
     if (!instance_ptr) return NULL;
 
@@ -86,7 +86,7 @@ virtual_identity *virtual_identity::get(virtual_class *instance_ptr)
     return NULL;
 }
 
-bool virtual_identity::check_instance(virtual_class *instance_ptr, bool allow_subclasses)
+bool virtual_identity::check_instance(virtual_ptr instance_ptr, bool allow_subclasses)
 {
     virtual_identity *actual = get(instance_ptr);
 
diff --git a/library/include/dfhack/DataDefs.h b/library/include/dfhack/DataDefs.h
index aa325958c..f106942fd 100644
--- a/library/include/dfhack/DataDefs.h
+++ b/library/include/dfhack/DataDefs.h
@@ -35,6 +35,12 @@ namespace DFHack
 {
     class virtual_class {};
 
+#ifdef _MSC_VER
+    typedef void *virtual_ptr;
+#else
+    typedef virtual_class *virtual_ptr;
+#endif
+
     class DFHACK_EXPORT virtual_identity {
         static virtual_identity *list;
         static std::map<void*, virtual_identity*> known;
@@ -51,9 +57,9 @@ namespace DFHack
     protected:
         virtual_identity(const char *dfhack_name, const char *original_name, virtual_identity *parent);
 
-        bool check_instance(virtual_class *instance_ptr, bool allow_subclasses);
+        bool check_instance(virtual_ptr instance_ptr, bool allow_subclasses);
 
-        static void *get_vtable(virtual_class *instance_ptr) { return *(void**)instance_ptr; }
+        static void *get_vtable(virtual_ptr instance_ptr) { return *(void**)instance_ptr; }
 
     public:
         const char *getName() { return dfhack_name; }
@@ -62,9 +68,9 @@ namespace DFHack
         virtual_identity *getParent() { return parent; }
         const std::vector<virtual_identity*> &getChildren() { return children; }
 
-        static virtual_identity *get(virtual_class *instance_ptr);
+        static virtual_identity *get(virtual_ptr instance_ptr);
 
-        bool is_instance(virtual_class *instance_ptr) {
+        bool is_instance(virtual_ptr instance_ptr) {
             if (!instance_ptr) return false;
             if (vtable_ptr) {
                 void *vtable = get_vtable(instance_ptr);
@@ -74,7 +80,7 @@ namespace DFHack
             return check_instance(instance_ptr, true);
         }
 
-        bool is_direct_instance(virtual_class *instance_ptr) {
+        bool is_direct_instance(virtual_ptr instance_ptr) {
             if (!instance_ptr) return false;
             return vtable_ptr ? (vtable_ptr == get_vtable(instance_ptr)) 
                               : check_instance(instance_ptr, false);
@@ -84,12 +90,12 @@ namespace DFHack
     };
 
     template<class T>
-    inline T *virtual_cast(virtual_class *ptr) {
+    inline T *virtual_cast(virtual_ptr ptr) {
         return T::_identity.is_instance(ptr) ? static_cast<T*>(ptr) : NULL;
     }
 
     template<class T>
-    inline T *strict_virtual_cast(virtual_class *ptr) {
+    inline T *strict_virtual_cast(virtual_ptr ptr) {
         return T::_identity.is_direct_instance(ptr) ? static_cast<T*>(ptr) : NULL;
     }