diff --git a/include/geos/simplify/PolygonHullSimplifier.h b/include/geos/simplify/PolygonHullSimplifier.h
index db0f03694b..db2a4b6b6e 100644
--- a/include/geos/simplify/PolygonHullSimplifier.h
+++ b/include/geos/simplify/PolygonHullSimplifier.h
@@ -104,7 +104,7 @@ class GEOS_DLL PolygonHullSimplifier
         , areaDeltaRatio(-1.0)
     {
         if (!geom->isPolygonal()) {
-            throw util::IllegalArgumentException("Input geometry must be  polygonal");
+            throw util::IllegalArgumentException("Input geometry must be polygonal");
         }
     };