diff --git a/normalize.cpp b/normalize.cpp
index 64532fe79d5e53e64f20eaca36b84012cb0ccb10..9d91104a41a1340489239d7799192df771f662bc 100644
--- a/normalize.cpp
+++ b/normalize.cpp
@@ -135,7 +135,7 @@ std::vector<eis::DataPoint> eis::reduceRegion(const std::vector<eis::DataPoint>&
 	eis::Log(eis::Log::DEBUG)<<"reduced range "<<start<<'-'<<end;
 
 	data.erase(data.begin(), data.begin()+start);
-	data.erase(data.begin()+end+1, data.end());
+	data.erase(data.begin()+end+1-start, data.end());
 
 	return data;
 }