diff --git a/factory/NTLconvert.cc b/factory/NTLconvert.cc
index 41ce9b2..e32093d 100644
--- a/factory/NTLconvert.cc
+++ b/factory/NTLconvert.cc
@@ -30,6 +30,7 @@
 #include <NTL/GF2EXFactoring.h>
 #include <NTL/tools.h>
 #include <NTL/mat_ZZ.h>
+#include <NTL/version.h>
 #include "int_int.h"
 #include <limits.h>
 #include "NTLconvert.h"
@@ -500,8 +501,14 @@ convertZZ2CF (const ZZ & a)
     return CanonicalForm(coeff_long);
   }
   else
-  {
-    long sizeofrep= ((long *) a.rep) [1];
+  { 
+    const long * rep =
+#if NTL_MAJOR_VERSION <= 6
+      static_cast<long *>( a.rep );
+#else
+      static_cast<long *>( a.rep.rep ); // what about NTL7?
+#endif
+    long sizeofrep= rep[1];
     bool lessZero= false;
     if (sizeofrep < 0)
     {
@@ -519,7 +526,7 @@ convertZZ2CF (const ZZ & a)
       cf_stringtemp_l= sizeofrep*sizeof(mp_limb_t)*2;
       cf_stringtemp= (unsigned char*) Alloc (cf_stringtemp_l);
     }
-    int cc= mpn_get_str (cf_stringtemp, 16, (mp_limb_t *) (((long *) (a.rep)) + 2), sizeofrep);
+    int cc= mpn_get_str (cf_stringtemp, 16, (mp_limb_t *) ((rep) + 2), sizeofrep);
 
     char* cf_stringtemp2;
     if (lessZero)