diff --git a/CHANGES b/CHANGES
index 1786aefd9a686ec116218c7fd8090c8a460c1ed2..83e4ee49f84a3614a4d84f4f4ea2579ea5e19c13 100644
--- a/CHANGES
+++ b/CHANGES
@@ -5,6 +5,9 @@
 
  Changes between 0.9.3a and 0.9.4
 
+  *) Make callbacks for key generation use void * instead of char *.
+     [Ben Laurie]
+
   *) Make S/MIME samples compile (not yet tested).
      [Ben Laurie]
 
diff --git a/apps/gendh.c b/apps/gendh.c
index b3c19581d350370dc6df0a80ece47dec90ab6d08..e5cb646bfb039e733263ea0dfc997e488a085994 100644
--- a/apps/gendh.c
+++ b/apps/gendh.c
@@ -74,7 +74,7 @@
 #undef PROG
 #define PROG gendh_main
 
-static void MS_CALLBACK dh_cb(int p, int n, char *arg);
+static void MS_CALLBACK dh_cb(int p, int n, void *arg);
 static long dh_load_rand(char *names);
 int MAIN(int argc, char **argv)
 	{
@@ -164,7 +164,7 @@ bad:
 
 	BIO_printf(bio_err,"Generating DH parameters, %d bit long strong prime, generator of %d\n",num,g);
 	BIO_printf(bio_err,"This is going to take a long time\n");
-	dh=DH_generate_parameters(num,g,dh_cb,(char *)bio_err);
+	dh=DH_generate_parameters(num,g,dh_cb,bio_err);
 		
 	if (dh == NULL) goto end;
 
@@ -184,7 +184,7 @@ end:
 	EXIT(ret);
 	}
 
-static void MS_CALLBACK dh_cb(int p, int n, char *arg)
+static void MS_CALLBACK dh_cb(int p, int n, void *arg)
 	{
 	char c='*';
 
diff --git a/apps/genrsa.c b/apps/genrsa.c
index 1cba9f59256c396fc52e14a741443d16e6dafbd3..9dfeb751447be417cd6b38fe18389a14149c66c3 100644
--- a/apps/genrsa.c
+++ b/apps/genrsa.c
@@ -75,7 +75,7 @@
 #undef PROG
 #define PROG genrsa_main
 
-static void MS_CALLBACK genrsa_cb(int p, int n, char *arg);
+static void MS_CALLBACK genrsa_cb(int p, int n, void *arg);
 static long gr_load_rand(char *names);
 int MAIN(int argc, char **argv)
 	{
@@ -194,7 +194,7 @@ bad:
 
 	BIO_printf(bio_err,"Generating RSA private key, %d bit long modulus\n",
 		num);
-	rsa=RSA_generate_key(num,f4,genrsa_cb,(char *)bio_err);
+	rsa=RSA_generate_key(num,f4,genrsa_cb,bio_err);
 		
 	if (randfile == NULL)
 		BIO_printf(bio_err,"unable to write 'random state'\n");
@@ -227,7 +227,7 @@ err:
 	EXIT(ret);
 	}
 
-static void MS_CALLBACK genrsa_cb(int p, int n, char *arg)
+static void MS_CALLBACK genrsa_cb(int p, int n, void *arg)
 	{
 	char c='*';
 
diff --git a/apps/req.c b/apps/req.c
index 052cae9804d901c9cea3596f41ecba7baead0b7b..dff16a6b92d96527a6b4a6dcc356d8316b7c782d 100644
--- a/apps/req.c
+++ b/apps/req.c
@@ -113,7 +113,7 @@ static int add_attribute_object(STACK_OF(X509_ATTRIBUTE) *n, char *text,
 				int max);
 static int add_DN_object(X509_NAME *n, char *text, char *def, char *value,
 	int nid,int min,int max);
-static void MS_CALLBACK req_cb(int p,int n,char *arg);
+static void MS_CALLBACK req_cb(int p,int n,void *arg);
 static int req_fix_data(int nid,int *type,int len,int min,int max);
 static int check_end(char *str, char *end);
 static int add_oid_section(LHASH *conf);
@@ -513,7 +513,7 @@ bad:
 			{
 			if (!EVP_PKEY_assign_RSA(pkey,
 				RSA_generate_key(newkey,0x10001,
-					req_cb,(char *)bio_err)))
+					req_cb,bio_err)))
 				goto end;
 			}
 		else
@@ -1111,7 +1111,7 @@ err:
 	return(0);
 	}
 
-static void MS_CALLBACK req_cb(int p, int n, char *arg)
+static void MS_CALLBACK req_cb(int p, int n, void *arg)
 	{
 	char c='*';
 
diff --git a/crypto/bn/bn.h b/crypto/bn/bn.h
index 230a591e422dde4e31393749cc9e00d33f2aaa45..4acd0174f65b36deb436bcdcfcd926318b1ba6e0 100644
--- a/crypto/bn/bn.h
+++ b/crypto/bn/bn.h
@@ -381,9 +381,9 @@ int 	BN_dec2bn(BIGNUM **a,char *str);
 int	BN_gcd(BIGNUM *r,BIGNUM *in_a,BIGNUM *in_b,BN_CTX *ctx);
 BIGNUM *BN_mod_inverse(BIGNUM *ret,BIGNUM *a, BIGNUM *n,BN_CTX *ctx);
 BIGNUM *BN_generate_prime(BIGNUM *ret,int bits,int strong,BIGNUM *add,
-		BIGNUM *rem,void (*callback)(int,int,char *),char *cb_arg);
-int	BN_is_prime(BIGNUM *p,int nchecks,void (*callback)(int,int,char *),
-		BN_CTX *ctx,char *cb_arg);
+		BIGNUM *rem,void (*callback)(int,int,void *),void *cb_arg);
+int	BN_is_prime(BIGNUM *p,int nchecks,void (*callback)(int,int,void *),
+		BN_CTX *ctx,void *cb_arg);
 void	ERR_load_BN_strings(void );
 
 BN_ULONG bn_mul_add_words(BN_ULONG *rp, BN_ULONG *ap, int num, BN_ULONG w);
diff --git a/crypto/bn/bn_prime.c b/crypto/bn/bn_prime.c
index 118eb35159bb6256ffded4de14d6a8933cf4a9cf..6fa0f9be1ee32b4767e8ed154832b88923601119 100644
--- a/crypto/bn/bn_prime.c
+++ b/crypto/bn/bn_prime.c
@@ -76,7 +76,7 @@ static int probable_prime_dh(BIGNUM *rnd, int bits,
 static int probable_prime_dh_strong(BIGNUM *rnd, int bits,
 	BIGNUM *add, BIGNUM *rem, BN_CTX *ctx);
 BIGNUM *BN_generate_prime(BIGNUM *ret, int bits, int strong, BIGNUM *add,
-	     BIGNUM *rem, void (*callback)(int,int,char *), char *cb_arg)
+	     BIGNUM *rem, void (*callback)(int,int,void *), void *cb_arg)
 	{
 	BIGNUM *rnd=NULL;
 	BIGNUM t;
@@ -151,8 +151,8 @@ err:
 	return(ret);
 	}
 
-int BN_is_prime(BIGNUM *a, int checks, void (*callback)(int,int,char *),
-	     BN_CTX *ctx_passed, char *cb_arg)
+int BN_is_prime(BIGNUM *a, int checks, void (*callback)(int,int,void *),
+	     BN_CTX *ctx_passed, void *cb_arg)
 	{
 	int i,j,c2=0,ret= -1;
 	BIGNUM *check;
diff --git a/crypto/dh/dh.h b/crypto/dh/dh.h
index 6a0a186fe346a9032c2dd1b8a8a28a2ef6efc5e9..affafd256bb1d206a26a5df33dfbf95e167ae6ac 100644
--- a/crypto/dh/dh.h
+++ b/crypto/dh/dh.h
@@ -112,7 +112,7 @@ DH *	DH_new(void);
 void	DH_free(DH *dh);
 int	DH_size(DH *dh);
 DH *	DH_generate_parameters(int prime_len,int generator,
-		void (*callback)(int,int,char *),char *cb_arg);
+		void (*callback)(int,int,void *),void *cb_arg);
 int	DH_check(DH *dh,int *codes);
 int	DH_generate_key(DH *dh);
 int	DH_compute_key(unsigned char *key,BIGNUM *pub_key,DH *dh);
diff --git a/crypto/dh/dh_gen.c b/crypto/dh/dh_gen.c
index 4d4aa69029b9a1e776c16b2d6489407036507097..7534ec40a016d5aca077127a50312b4e510988eb 100644
--- a/crypto/dh/dh_gen.c
+++ b/crypto/dh/dh_gen.c
@@ -84,7 +84,7 @@
  */
 
 DH *DH_generate_parameters(int prime_len, int generator,
-	     void (*callback)(int,int,char *), char *cb_arg)
+	     void (*callback)(int,int,void *), void *cb_arg)
 	{
 	BIGNUM *p=NULL,*t1,*t2;
 	DH *ret=NULL;
diff --git a/crypto/dh/dhtest.c b/crypto/dh/dhtest.c
index 370784b9642cb9193c269363a7ae3e5cd1a7ad2d..a3f4692eca9d76079ec821579d66ef5c59d7a4db 100644
--- a/crypto/dh/dhtest.c
+++ b/crypto/dh/dhtest.c
@@ -81,7 +81,7 @@ int main(int argc, char *argv[])
 #define MS_CALLBACK
 #endif
 
-static void MS_CALLBACK cb(int p, int n, char *arg);
+static void MS_CALLBACK cb(int p, int n, void *arg);
 #ifdef NO_STDIO
 #define APPS_WIN16
 #include "bss_file.c"
@@ -104,7 +104,7 @@ int main(int argc, char *argv[])
 	if (out == NULL) exit(1);
 	BIO_set_fp(out,stdout,BIO_NOCLOSE);
 
-	a=DH_generate_parameters(64,DH_GENERATOR_5,cb,(char *)out);
+	a=DH_generate_parameters(64,DH_GENERATOR_5,cb,out);
 	if (a == NULL) goto err;
 
 	BIO_puts(out,"\np    =");
@@ -171,7 +171,7 @@ err:
 	return(ret);
 	}
 
-static void MS_CALLBACK cb(int p, int n, char *arg)
+static void MS_CALLBACK cb(int p, int n, void *arg)
 	{
 	char c='*';
 
diff --git a/crypto/rsa/rsa.h b/crypto/rsa/rsa.h
index 2f53ff04b9e065352d5755da613d7c5ad8ec5608..d38d7f92fe6f858eca0ffec7be61c9a88064d665 100644
--- a/crypto/rsa/rsa.h
+++ b/crypto/rsa/rsa.h
@@ -145,7 +145,7 @@ RSA *	RSA_new(void);
 RSA *	RSA_new_method(RSA_METHOD *method);
 int	RSA_size(RSA *);
 RSA *	RSA_generate_key(int bits, unsigned long e,void
-		(*callback)(int,int,char *),char *cb_arg);
+		(*callback)(int,int,void *),void *cb_arg);
 	/* next 4 return -1 on error */
 int	RSA_public_encrypt(int flen, unsigned char *from,
 		unsigned char *to, RSA *rsa,int padding);
diff --git a/crypto/rsa/rsa_gen.c b/crypto/rsa/rsa_gen.c
index 8f3279eee1d73c6b3ca3b15f963dfa38317909ae..89e2f2e2e2d527c594695d425dba3c0f7eebec47 100644
--- a/crypto/rsa/rsa_gen.c
+++ b/crypto/rsa/rsa_gen.c
@@ -63,7 +63,7 @@
 #include <openssl/rsa.h>
 
 RSA *RSA_generate_key(int bits, unsigned long e_value,
-	     void (*callback)(int,int,char *), char *cb_arg)
+	     void (*callback)(int,int,void *), void *cb_arg)
 	{
 	RSA *rsa=NULL;
 	BIGNUM *r0=NULL,*r1=NULL,*r2=NULL,*r3=NULL,*tmp;