diff --git a/opennurbs_curve.cpp b/opennurbs_curve.cpp
index 3e82a01..46de1b9 100644
--- a/opennurbs_curve.cpp
+++ b/opennurbs_curve.cpp
@@ -1413,11 +1413,11 @@ bool ON_Curve::Ev2Der( // returns false if unable to evaluate
 //
 
 
-static
-ON::eCurveType ON_CurveType( const ON_Curve* curve )
+ON::eCurveType ON_Curve::ON_CurveType() const
 {
   const ON_ClassId* curve_id = &ON_CLASS_RTTI(ON_Curve);
-  const ON_ClassId* id = curve->ClassId();
+
+  const ON_ClassId* id = this->ClassId();
 
   // "fake virtual" handling of fast/easy special cases
   while (0 != id && curve_id != id )
@@ -1496,7 +1496,7 @@ bool ON_MatchCurveEnds( ON_Curve* curve0,
         ON_3dPoint Q0 = ON_3dPoint::UnsetPoint;
         ON_3dPoint Q1 = ON_3dPoint::UnsetPoint;
         ON_Curve* c = i ? curve1 : curve0;
-        ON::eCurveType ct = ON_CurveType(c);
+        ON::eCurveType ct = c->ON_CurveType();
         int e = i ? end1 : end0;
         while ( ON::ctPolycurve == ct )
         {
@@ -1507,7 +1507,7 @@ bool ON_MatchCurveEnds( ON_Curve* curve0,
           c = polycurve->SegmentCurve(e?(polycurve->Count()-1):0);
           if( 0 == c )
             return false;
-          ct = ON_CurveType(c);
+          ct = c->ON_CurveType();
         }
         seg[i] = c;
         switch(ct)
@@ -1714,7 +1714,7 @@ bool ON_ForceMatchCurveEnds(ON_Curve& Crv0, int end0, ON_Curve& Crv1, int end1)
   for ( i = 0; i<2; i++ )
   {
     ON_Curve* c = i ? &Crv1 : &Crv0;
-    ct[i] = ON_CurveType(c);
+    ct[i] = c->ON_CurveType();
     int e = i ? end1 : end0;
     while ( ON::ctPolycurve == ct[i] )
     {
@@ -1725,7 +1725,7 @@ bool ON_ForceMatchCurveEnds(ON_Curve& Crv0, int end0, ON_Curve& Crv1, int end1)
       c = polycurve->SegmentCurve(e?(polycurve->Count()-1):0);
       if( 0 == c )
         return false;
-      ct[i] = ON_CurveType(c);
+      ct[i] = c->ON_CurveType();
     }
     if (c->IsClosed())
       return false;
@@ -1778,7 +1778,7 @@ bool ON_ForceMatchCurveEnds(ON_Curve& Crv0, int end0, ON_Curve& Crv1, int end1)
     else {
       //23 Jan 2018 - Chuck - If yanking a polycurve segment at the join causes
       //that seg to be tiny, remove it and try again. See RH-43661
-      if (ON_CurveType(&Crv0) == ON::ctPolycurve){
+      if (Crv0.ON_CurveType() == ON::ctPolycurve){
         ON_PolyCurve* polycurve = ON_PolyCurve::Cast(&Crv0);
         if (polycurve->Count() > 1 && FastIsShort(*seg[0], 10.0*ON_ZERO_TOLERANCE))
           bTryAgain = (end0) ? polycurve->Remove() : polycurve->Remove(0);
@@ -1792,7 +1792,7 @@ bool ON_ForceMatchCurveEnds(ON_Curve& Crv0, int end0, ON_Curve& Crv1, int end1)
     else {
       //23 Jan 2018 - Chuck - If yanking a polycurve segment at the join causes
       //that seg to be tiny, remove it and try again. See RH-43661
-      if (ON_CurveType(&Crv1) == ON::ctPolycurve){
+      if (Crv1.ON_CurveType() == ON::ctPolycurve){
         ON_PolyCurve* polycurve = ON_PolyCurve::Cast(&Crv1);
         if (polycurve->Count() > 1 && FastIsShort(*seg[1], 10.0*ON_ZERO_TOLERANCE)){
           bool bRem = (end1) ? polycurve->Remove() : polycurve->Remove(0);
diff --git a/opennurbs_curve.h b/opennurbs_curve.h
index efe9a68..188ae3c 100644
--- a/opennurbs_curve.h
+++ b/opennurbs_curve.h
@@ -140,6 +140,8 @@ public:
   //   ON::curve_object
   ON::object_type ObjectType() const override;
 
+  ON::eCurveType ON_Curve::ON_CurveType() const ;
+
   // virtual ON_Geometry GetTightBoundingBox override		
   bool GetTightBoundingBox( class ON_BoundingBox& tight_bbox, bool bGrowBox = false, const class ON_Xform* xform = nullptr ) const override;