--- src/coverage/CoverageRingEdges.cpp.orig
+++ src/coverage/CoverageRingEdges.cpp
@@ -14,6 +14,7 @@
  **********************************************************************/
 
 #include <map>
+#include <unordered_map>
 
 #include <geos/coverage/CoverageBoundarySegmentFinder.h>
 #include <geos/coverage/CoverageEdge.h>