diff --git a/source/glest_game/types/unit_type.cpp b/source/glest_game/types/unit_type.cpp
index a9b264d0..960b19c5 100644
--- a/source/glest_game/types/unit_type.cpp
+++ b/source/glest_game/types/unit_type.cpp
@@ -250,6 +250,14 @@ void UnitType::loaddd(int id,const string &dir, const TechTree *techTree,
 		}
 		addItemToVault(&(this->epRegeneration),this->epRegeneration);
 
+		// Check that we don't use both start-value and start-percentage, as they are mutually
+		// exclusive
+		if(parametersNode->getChild("max-ep")->hasAttribute("start-value") &&
+				parametersNode->getChild("max-ep")->hasAttribute("start-percentage")) {
+					throw megaglest_runtime_error("Unit " + name +
+							" has both start-value and start-percentage for EP", validationMode);
+		}
+
 		//startEpValue -- the *absolute* value to use for starting EP
 		if(parametersNode->getChild("max-ep")->hasAttribute("start-value")) {
 			//checkItemInVault(&(this->startEp),this->startEp);