diff --git a/apps/openmw/mwworld/timestamp.cpp b/apps/openmw/mwworld/timestamp.cpp
index 3ffb384967..22fa504d45 100644
--- a/apps/openmw/mwworld/timestamp.cpp
+++ b/apps/openmw/mwworld/timestamp.cpp
@@ -2,6 +2,7 @@
 
 #include <cmath>
 #include <stdexcept>
+#include <string>
 
 #include <components/esm/defs.hpp>
 
@@ -11,8 +12,8 @@ namespace MWWorld
         : mHour(hour)
         , mDay(day)
     {
-        if (hour < 0 || hour >= 24 || day < 0)
-            throw std::runtime_error("invalid time stamp");
+        if (hour < 0 || hour >= 24)
+            throw std::runtime_error("invalid time stamp hour: " + std::to_string(hour));
     }
 
     float TimeStamp::getHour() const