diff --git a/arangod/Aql/ExecutionNode.cpp b/arangod/Aql/ExecutionNode.cpp
index ab7781e578..d02f8a8f65 100644
--- a/arangod/Aql/ExecutionNode.cpp
+++ b/arangod/Aql/ExecutionNode.cpp
@@ -1401,7 +1401,7 @@ double IndexRangeNode::estimateCost (size_t& nrItems) const {
   
   if (_index->type == TRI_IDX_TYPE_EDGE_INDEX) {
     // always an equality lookup
-    nrItems = incoming * _ranges.size() * docCount / EqualityReductionFactor;
+    nrItems = incoming * _ranges.size() * docCount / static_cast<size_t>(EqualityReductionFactor);
     return dependencyCost + nrItems;
   }