diff --git a/src/openrct2/scripting/bindings/world/ScResearch.hpp b/src/openrct2/scripting/bindings/world/ScResearch.hpp
index 41b7b1efc6..3236b54421 100644
--- a/src/openrct2/scripting/bindings/world/ScResearch.hpp
+++ b/src/openrct2/scripting/bindings/world/ScResearch.hpp
@@ -145,7 +145,7 @@ namespace OpenRCT2::Scripting
         {
             if (gResearchProgressStage == RESEARCH_STAGE_INITIAL_RESEARCH || gResearchExpectedDay == 255)
                 return ToDuk(_context, nullptr);
-            return ToDuk(_context, gResearchExpectedDay);
+            return ToDuk(_context, gResearchExpectedDay + 1);
         }
 
         DukValue lastResearchedItem_get() const