diff --git a/crypto/bn/bn_prime.c b/crypto/bn/bn_prime.c
index 5bab019553..7b25979dd1 100644
--- a/crypto/bn/bn_prime.c
+++ b/crypto/bn/bn_prime.c
@@ -377,14 +377,14 @@ static int witness(BIGNUM *w, const BIGNUM *a, const BIGNUM *a1,
 static int probable_prime(BIGNUM *rnd, int bits)
 	{
 	int i;
-	BN_ULONG mods[NUMPRIMES];
+	prime_t mods[NUMPRIMES];
 	BN_ULONG delta,maxdelta;
 
 again:
 	if (!BN_rand(rnd,bits,1,1)) return(0);
 	/* we now have a random number 'rand' to test. */
 	for (i=1; i<NUMPRIMES; i++)
-		mods[i]=BN_mod_word(rnd,(BN_ULONG)primes[i]);
+		mods[i]=(prime_t)BN_mod_word(rnd,(BN_ULONG)primes[i]);
 	maxdelta=BN_MASK2 - primes[NUMPRIMES-1];
 	delta=0;
 	loop: for (i=1; i<NUMPRIMES; i++)
diff --git a/crypto/bn/bn_prime.h b/crypto/bn/bn_prime.h
index b7cf9a9bfe..51d2194feb 100644
--- a/crypto/bn/bn_prime.h
+++ b/crypto/bn/bn_prime.h
@@ -58,10 +58,12 @@
 
 #ifndef EIGHT_BIT
 #define NUMPRIMES 2048
+typedef unsigned short prime_t;
 #else
 #define NUMPRIMES 54
+typedef unsigned char prime_t;
 #endif
-static const unsigned int primes[NUMPRIMES]=
+static const prime_t primes[NUMPRIMES]=
 	{
 	   2,   3,   5,   7,  11,  13,  17,  19,
 	  23,  29,  31,  37,  41,  43,  47,  53,
diff --git a/crypto/bn/bn_prime.pl b/crypto/bn/bn_prime.pl
index e583d1d53b..3fafb6f3e9 100644
--- a/crypto/bn/bn_prime.pl
+++ b/crypto/bn/bn_prime.pl
@@ -101,10 +101,12 @@ for ($i=0; $i <= $#primes; $i++)
 
 printf "#ifndef EIGHT_BIT\n";
 printf "#define NUMPRIMES %d\n",$num;
+printf "typedef unsigned short prime_t;\n";
 printf "#else\n";
 printf "#define NUMPRIMES %d\n",$eight;
+printf "typedef unsigned char prime_t;\n";
 printf "#endif\n";
-print "static const unsigned int primes[NUMPRIMES]=\n\t{\n\t";
+print "static const prime_t primes[NUMPRIMES]=\n\t{\n\t";
 $init=0;
 for ($i=0; $i <= $#primes; $i++)
 	{