diff --git a/src/mapper/mapper.cc b/src/mapper/mapper.cc
index 4b3aea2..65af3cf 100644
--- a/src/mapper/mapper.cc
+++ b/src/mapper/mapper.cc
@@ -18,6 +18,7 @@
 namespace fallout {
 
 static int categoryHide();
+static int categoryToggleState();
 static int categoryUnhide();
 static bool proto_user_is_librarian();
 static void redraw_toolname();
@@ -54,6 +55,16 @@ int categoryHide()
     return 0;
 }
 
+// 0x487768
+int categoryToggleState()
+{
+    if (categoryIsHidden) {
+        return categoryUnhide();
+    } else {
+        return categoryHide();
+    }
+}
+
 // 0x487774
 int categoryUnhide()
 {