diff --git a/src/mapper/mapper.cc b/src/mapper/mapper.cc
index 38cfa5e..4b3aea2 100644
--- a/src/mapper/mapper.cc
+++ b/src/mapper/mapper.cc
@@ -17,6 +17,7 @@
 
 namespace fallout {
 
+static int categoryHide();
 static int categoryUnhide();
 static bool proto_user_is_librarian();
 static void redraw_toolname();
@@ -40,6 +41,19 @@ unsigned char* tool;
 // 0x6EC4AC
 int tool_win;
 
+// 0x487728
+int categoryHide()
+{
+    if (categoryWin == -1) {
+        return -1;
+    }
+
+    windowHide(categoryWin);
+    categoryIsHidden = true;
+
+    return 0;
+}
+
 // 0x487774
 int categoryUnhide()
 {