diff --git a/library/Core.cpp b/library/Core.cpp
index 1d2a76026..e8c43b7f5 100644
--- a/library/Core.cpp
+++ b/library/Core.cpp
@@ -71,6 +71,7 @@ using namespace DFHack;
 using namespace tthread;
 using namespace df::enums;
 using df::global::init;
+using df::global::world;
 
 // FIXME: A lot of code in one file, all doing different things... there's something fishy about it.
 
@@ -1113,8 +1114,18 @@ int Core::Update()
     return 0;
 };
 
+extern bool buildings_do_onupdate;
+void buildings_onStateChange(color_ostream &out, state_change_event event);
+void buildings_onUpdate(color_ostream &out);
+
+static int buildings_timer = 0;
+
 void Core::onUpdate(color_ostream &out)
 {
+    // convert building reagents
+    if (buildings_do_onupdate && (++buildings_timer & 1))
+        buildings_onUpdate(out);
+
     // notify all the plugins that a game tick is finished
     plug_mgr->OnUpdate(out);
 
@@ -1124,6 +1135,8 @@ void Core::onUpdate(color_ostream &out)
 
 void Core::onStateChange(color_ostream &out, state_change_event event)
 {
+    buildings_onStateChange(out, event);
+
     plug_mgr->OnStateChange(out, event);
 
     Lua::Core::onStateChange(out, event);
diff --git a/library/modules/Buildings.cpp b/library/modules/Buildings.cpp
index d2b3e3527..e0afc56ed 100644
--- a/library/modules/Buildings.cpp
+++ b/library/modules/Buildings.cpp
@@ -87,6 +87,58 @@ static uint8_t *getExtentTile(df::building_extents &extent, df::coord2d tile)
     return &extent.extents[dx + dy*extent.width];
 }
 
+/*
+ * A monitor to work around this bug, in its application to buildings:
+ *
+ * http://www.bay12games.com/dwarves/mantisbt/view.php?id=1416
+ */
+bool buildings_do_onupdate = false;
+
+void buildings_onStateChange(color_ostream &out, state_change_event event)
+{
+    switch (event) {
+    case SC_MAP_LOADED:
+        buildings_do_onupdate = true;
+        break;
+    case SC_MAP_UNLOADED:
+        buildings_do_onupdate = false;
+        break;
+    default:
+        break;
+    }
+}
+
+void buildings_onUpdate(color_ostream &out)
+{
+    buildings_do_onupdate = false;
+
+    df::job_list_link *link = world->job_list.next;
+    for (; link; link = link->next) {
+        df::job *job = link->item;
+
+        if (job->job_type != job_type::ConstructBuilding)
+            continue;
+        if (job->job_items.empty())
+            continue;
+
+        buildings_do_onupdate = true;
+
+        for (size_t i = 0; i < job->items.size(); i++)
+        {
+            df::job_item_ref *iref = job->items[i];
+            if (iref->role != df::job_item_ref::Reagent)
+                continue;
+            df::job_item *item = vector_get(job->job_items, iref->job_item_idx);
+            if (!item)
+                continue;
+            // Convert Reagent to Hauled, while decrementing quantity
+            item->quantity = std::max(0, item->quantity-1);
+            iref->role = df::job_item_ref::Hauled;
+            iref->job_item_idx = -1;
+        }
+    }
+}
+
 uint32_t Buildings::getNumBuildings()
 {
     return world->buildings.all.size();
@@ -906,6 +958,8 @@ bool Buildings::constructWithFilters(df::building *bld, std::vector<df::job_item
             bld->mat_index = items[i]->mat_index;
     }
 
+    buildings_do_onupdate = true;
+
     createDesign(bld, rough);
     return true;
 }
@@ -969,3 +1023,4 @@ bool Buildings::deconstruct(df::building *bld)
 
     return true;
 }
+