diff --git a/src/mod25638.c b/src/mod25638.c
index 2a617a2..9bdfe4a 100644
--- a/src/mod25638.c
+++ b/src/mod25638.c
@@ -69,8 +69,8 @@
 2^256 - 32 - 4 - 2
   0 ffffffff ffffffff ffffffff ffffffff ffffffff ffffffff ffffffff ffffffda
 */
-const bn256 n25638 = { {0xffffffda, 0xffffffff, 0xffffffff, 0xffffffff,
-			0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff } };
+const bn256 n25638[1] = { {0xffffffda, 0xffffffff, 0xffffffff, 0xffffffff,
+			   0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff } };
 
 
 /*
@@ -93,9 +93,9 @@ mod25638_add (bn256 *X, const bn256 *A, const bn256 *B)
 
   carry = bn256_add (X, A, B);
   if (carry)
-    bn256_sub (X, X, N25638);
+    bn256_sub (X, X, n25638);
   else
-    bn256_sub (tmp, X, N25638);
+    bn256_sub (tmp, X, n25638);
 }
 
 /**
@@ -109,9 +109,9 @@ mod25638_sub (bn256 *X, const bn256 *A, const bn256 *B)
 
   borrow = bn256_sub (X, A, B);
   if (borrow)
-    bn256_add (X, X, N25638);
+    bn256_add (X, X, n25638);
   else
-    bn256_add (tmp, X, N25638);
+    bn256_add (tmp, X, n25638);
 }
 
 
diff --git a/src/mod25638.h b/src/mod25638.h
index d4b293e..dd19481 100644
--- a/src/mod25638.h
+++ b/src/mod25638.h
@@ -1,5 +1,4 @@
-extern const bn256 n25638;
-#define N25638 (&n25638)
+extern const bn256 *n25638;
 
 void mod25638_add (bn256 *X, const bn256 *A, const bn256 *B);
 void mod25638_sub (bn256 *X, const bn256 *A, const bn256 *B);