diff --git a/API_GdbCreateCurve.cpp b/API_GdbCreateCurve.cpp
index cd0c88f..d39b855 100644
--- a/API_GdbCreateCurve.cpp
+++ b/API_GdbCreateCurve.cpp
@@ -129,14 +129,28 @@ int
 __stdcall EgtCreateArc3P( int nParentId, const double ptP1[3],
                           const double ptP2[3], const double ptP3[3], int nRefType)
 {
+   if ( ptP1 == nullptr  ||  ptP2 == nullptr  ||  ptP3 == nullptr)
+      return GDB_ID_NULL ;
    return ExeCreateArc3P( nParentId, ptP1, ptP2, ptP3, nRefType) ;
 }
 
+//-------------------------------------------------------------------------------
+int
+__stdcall EgtCreateArc2PR( int nParentId, const double ptStart[3], const double ptEnd[3],
+                           double dRad, BOOL bCCW, int nRefType)
+{
+   if ( ptStart == nullptr  ||  ptEnd == nullptr)
+      return GDB_ID_NULL ;
+   return ExeCreateArc2PR( nParentId, ptStart, ptEnd, dRad, ( bCCW != FALSE), nRefType) ;
+}
+
 //-------------------------------------------------------------------------------
 int
 __stdcall EgtCreateArc2PD( int nParentId, const double ptStart[3], const double ptEnd[3],
                            double dDirSDeg, int nRefType)
 {
+   if ( ptStart == nullptr  ||  ptEnd == nullptr)
+      return GDB_ID_NULL ;
    return ExeCreateArc2PD( nParentId, ptStart, ptEnd, dDirSDeg, nRefType) ;
 }
 
@@ -146,6 +160,8 @@ __stdcall EgtCreateArc2PDEx( int nParentId, const double ptStart[3],
                              const double ptEnd[3], int nSep, int nId,
                              double dDirSDeg, int nRefType)
 {
+   if ( ptStart == nullptr  ||  ptEnd == nullptr)
+      return GDB_ID_NULL ;
    return ExeCreateArc2PDEx( nParentId, ptStart, ptEnd, nSep, nId, dDirSDeg, nRefType) ;
 }
 
@@ -154,6 +170,8 @@ int
 __stdcall EgtCreateArc2PV( int nParentId, const double ptStart[3], const double ptEnd[3],
                            const double vtDirS[3], int nRefType)
 {
+   if ( ptStart == nullptr  ||  ptEnd == nullptr)
+      return GDB_ID_NULL ;
    return ExeCreateArc2PV( nParentId, ptStart, ptEnd, vtDirS, nRefType) ;
 }
 
@@ -162,6 +180,8 @@ int
 __stdcall EgtCreateBiArc( int nParentId, const double ptStart[3], const double ptEnd[3],
                           double dDirSDeg, double dDirEDeg, double dPar, int nRefType)
 {
+   if ( ptStart == nullptr  ||  ptEnd == nullptr)
+      return GDB_ID_NULL ;
    return ExeCreateBiArc( nParentId, ptStart, ptEnd, dDirSDeg, dDirEDeg, dPar, nRefType) ;
 }
 
diff --git a/EgtInterface.rc b/EgtInterface.rc
index 47382b0..1045867 100644
Binary files a/EgtInterface.rc and b/EgtInterface.rc differ