diff --git a/src/gui/game/PropertyTool.cpp b/src/gui/game/PropertyTool.cpp
index ed660a319..5c56e3e4a 100644
--- a/src/gui/game/PropertyTool.cpp
+++ b/src/gui/game/PropertyTool.cpp
@@ -25,6 +25,10 @@
 
 void ParseFloatProperty(String value, float &out)
 {
+	if (!value.size())
+	{
+		throw std::out_of_range("empty string");
+	}
 	if (value.EndsWith("C"))
 	{
 		float v = value.SubstrFromEnd(1).ToNumber<float>();
diff --git a/src/gui/options/OptionsView.cpp b/src/gui/options/OptionsView.cpp
index 3fb2bb8a5..2e9afb14e 100644
--- a/src/gui/options/OptionsView.cpp
+++ b/src/gui/options/OptionsView.cpp
@@ -476,7 +476,7 @@ void OptionsView::UpdateAirTemp(String temp, bool isDefocus)
 		ambientAirTemp->SetText(sb.Build());
 	}
 	// Out of range temperatures are invalid, preview should go away
-	else if (airTemp < MIN_TEMP || airTemp > MAX_TEMP)
+	else if (isValid && (airTemp < MIN_TEMP || airTemp > MAX_TEMP))
 		isValid = false;
 
 	// If valid, set temp