diff --git a/vm/bignum.cpp b/vm/bignum.cpp
index 03b34edd97..f61b44340e 100755
--- a/vm/bignum.cpp
+++ b/vm/bignum.cpp
@@ -1980,14 +1980,14 @@ int bignum_unsigned_logbitp(int shift, bignum * bignum)
 }
 
 /* Allocates memory */
-bignum *factorvm::digit_stream_to_bignum(unsigned int n_digits, unsigned int (*producer)(unsigned int), unsigned int radix, int negative_p)
+bignum *factorvm::digit_stream_to_bignum(unsigned int n_digits, unsigned int (*producer)(unsigned int, factorvm*), unsigned int radix, int negative_p)
 {
   BIGNUM_ASSERT ((radix > 1) && (radix <= BIGNUM_RADIX_ROOT));
   if (n_digits == 0)
     return (BIGNUM_ZERO ());
   if (n_digits == 1)
     {
-      fixnum digit = ((fixnum) ((*producer) (0)));
+		fixnum digit = ((fixnum) ((*producer) (0,this)));
       return (fixnum_to_bignum (negative_p ? (- digit) : digit));
     }
   {
@@ -2009,14 +2009,14 @@ bignum *factorvm::digit_stream_to_bignum(unsigned int n_digits, unsigned int (*p
         {
           bignum_destructive_scale_up (result, ((bignum_digit_type) radix));
           bignum_destructive_add
-            (result, ((bignum_digit_type) ((*producer) (n_digits))));
+			  (result, ((bignum_digit_type) ((*producer) (n_digits,this))));
         }
       return (bignum_trim (result));
     }
   }
 }
 
-bignum *digit_stream_to_bignum(unsigned int n_digits, unsigned int (*producer)(unsigned int), unsigned int radix, int negative_p)
+bignum *digit_stream_to_bignum(unsigned int n_digits, unsigned int (*producer)(unsigned int, factorvm*), unsigned int radix, int negative_p)
 {
 	return vm->digit_stream_to_bignum(n_digits,producer,radix,negative_p);
 }
diff --git a/vm/bignum.hpp b/vm/bignum.hpp
index 5f502dcc22..8f21702f1a 100644
--- a/vm/bignum.hpp
+++ b/vm/bignum.hpp
@@ -119,8 +119,9 @@ void        bignum_negate_magnitude(bignum *);
 bignum * bignum_integer_length(bignum * arg1);
 int bignum_unsigned_logbitp(int shift, bignum * bignum);
 int bignum_logbitp(int shift, bignum * arg);
+struct factorvm;
 bignum * digit_stream_to_bignum(unsigned int n_digits,
-                                   unsigned int (*producer)(unsigned int),
+								unsigned int (*producer)(unsigned int,factorvm*),
                                    unsigned int radix,
                                    int negative_p);
 
diff --git a/vm/math.cpp b/vm/math.cpp
index ed556f268a..98188059f6 100755
--- a/vm/math.cpp
+++ b/vm/math.cpp
@@ -359,9 +359,9 @@ unsigned int factorvm::bignum_producer(unsigned int digit)
 	return *(ptr + digit);
 }
 
-unsigned int bignum_producer(unsigned int digit)
+unsigned int bignum_producer(unsigned int digit, factorvm *myvm)
 {
-	return vm->bignum_producer(digit);
+	return myvm->bignum_producer(digit);
 }
 
 inline void factorvm::vmprim_byte_array_to_bignum()
diff --git a/vm/vm.hpp b/vm/vm.hpp
index 42a250832c..0f7a26c020 100644
--- a/vm/vm.hpp
+++ b/vm/vm.hpp
@@ -120,7 +120,7 @@ struct factorvm {
 	bignum *bignum_integer_length(bignum * x);
 	int bignum_logbitp(int shift, bignum * arg);
 	int bignum_unsigned_logbitp(int shift, bignum * bignum);
-	bignum *digit_stream_to_bignum(unsigned int n_digits, unsigned int (*producer)(unsigned int), unsigned int radix, int negative_p);
+	bignum *digit_stream_to_bignum(unsigned int n_digits, unsigned int (*producer)(unsigned int, factorvm *), unsigned int radix, int negative_p);
 
 	//data_heap
 	bool secure_gc;  /* Set by the -securegc command line argument */