diff --git a/src/avp/dynamics.c b/src/avp/dynamics.c
index edb5ae9..bb38de4 100644
--- a/src/avp/dynamics.c
+++ b/src/avp/dynamics.c
@@ -3272,7 +3272,7 @@ static void TestObjectWithStaticBoundingBox(DISPLAYBLOCK *objectPtr)
 
 static int IsPolygonWithinDynamicBoundingBox(const struct ColPolyTag *polyPtr)
 {
-	VECTORCH *vertices = polyPtr->PolyPoint;
+	const VECTORCH *vertices = polyPtr->PolyPoint;
 
 	if (polyPtr->NumberOfVertices==4)
 	{
@@ -3353,7 +3353,7 @@ static int IsPolygonWithinDynamicBoundingBox(const struct ColPolyTag *polyPtr)
 
 static int IsPolygonWithinStaticBoundingBox(const struct ColPolyTag *polyPtr)
 {
-	VECTORCH *vertices = polyPtr->PolyPoint;
+	const VECTORCH *vertices = polyPtr->PolyPoint;
 
 	if (polyPtr->NumberOfVertices==4)
 	{