diff --git a/src/openrct2/object/SmallSceneryObject.cpp b/src/openrct2/object/SmallSceneryObject.cpp
index f9c2a49730..4294c20fae 100644
--- a/src/openrct2/object/SmallSceneryObject.cpp
+++ b/src/openrct2/object/SmallSceneryObject.cpp
@@ -17,10 +17,12 @@
 #include "../core/IStream.hpp"
 #include "../core/Math.hpp"
 #include "../core/Memory.hpp"
+#include "../core/String.hpp"
 #include "SmallSceneryObject.h"
 
 #include "../drawing/drawing.h"
 #include "../localisation/language.h"
+#include "../world/scenery.h"
 
 SmallSceneryObject::~SmallSceneryObject()
 {
@@ -81,6 +83,8 @@ void SmallSceneryObject::Load()
     {
         _legacyType.small_scenery.frame_offsets = _frameOffsets;
     }
+
+    PerformFixes();
 }
 
 void SmallSceneryObject::Unload()
@@ -150,3 +154,23 @@ uint8 * SmallSceneryObject::ReadFrameOffsets(IStream * stream)
     data.push_back(frameOffset);
     return Memory::Duplicate(data.data(), data.size());
 }
+
+void SmallSceneryObject::PerformFixes()
+{
+    std::string identifier = GetIdentifier();
+
+    // ToonTowner's base blocks. Make them allow supports on top and put them in the Walls and Roofs group.
+    if (String::Equals(identifier, "XXBBCL01") ||
+        String::Equals(identifier, "XXBBMD01") ||
+        String::Equals(identifier, "XXBBBR01") ||
+        String::Equals(identifier, "ARBASE2 "))
+    {
+        static const rct_object_entry * scgWalls = object_list_find_by_name("SCGWALLS");
+        if (scgWalls != nullptr)
+        {
+            SetPrimarySceneryGroup((rct_object_entry *)scgWalls);
+        }
+
+        _legacyType.small_scenery.flags |= SMALL_SCENERY_FLAG_BUILD_DIRECTLY_ONTOP;
+    }
+}
diff --git a/src/openrct2/object/SmallSceneryObject.h b/src/openrct2/object/SmallSceneryObject.h
index ee7a7a869a..daaa21dd50 100644
--- a/src/openrct2/object/SmallSceneryObject.h
+++ b/src/openrct2/object/SmallSceneryObject.h
@@ -42,6 +42,7 @@ public:
 
 private:
     static uint8 * ReadFrameOffsets(IStream * stream);
+    void PerformFixes();
 };
 
 #endif
diff --git a/src/openrct2/world/scenery.h b/src/openrct2/world/scenery.h
index fd6585d5d0..2097608776 100644
--- a/src/openrct2/world/scenery.h
+++ b/src/openrct2/world/scenery.h
@@ -73,7 +73,7 @@ typedef enum {
     SMALL_SCENERY_FLAG_NO_SUPPORTS = (1 << 20),                 // 0x100000
     SMALL_SCENERY_FLAG_VISIBLE_WHEN_ZOOMED = (1 << 21),         // 0x200000
     SMALL_SCENERY_FLAG_COG = (1 << 22),                         // 0x400000
-    SMALL_SCENERY_FLAG_BUILD_DIRECTLY_ONTOP = (1 << 23),        // 0x800000
+    SMALL_SCENERY_FLAG_BUILD_DIRECTLY_ONTOP = (1 << 23),        // 0x800000; means supports can be built on this object. Used for base blocks.
     SMALL_SCENERY_FLAG_HALF_SPACE = (1 << 24),                  // 0x1000000
     SMALL_SCENERY_FLAG_THREE_QUARTERS = (1 << 25),              // 0x2000000
     SMALL_SCENERY_FLAG_PAINT_SUPPORTS = (1 << 26),              // 0x4000000; used for scenery items which are support structures