diff --git a/crypto/asn1/a_gentm.c b/crypto/asn1/a_gentm.c
index cd09f68b3..e9d61bfe8 100644
--- a/crypto/asn1/a_gentm.c
+++ b/crypto/asn1/a_gentm.c
@@ -115,7 +115,7 @@ err:
 
 #endif
 
-int ASN1_GENERALIZEDTIME_check(ASN1_GENERALIZEDTIME *d)
+int ASN1_GENERALIZEDTIME_check(const ASN1_GENERALIZEDTIME *d)
 	{
 	static int min[9]={ 0, 0, 1, 1, 0, 0, 0, 0, 0};
 	static int max[9]={99, 99,12,31,23,59,59,12,59};
diff --git a/crypto/asn1/a_time.c b/crypto/asn1/a_time.c
index 7348da945..1b51a0752 100644
--- a/crypto/asn1/a_time.c
+++ b/crypto/asn1/a_time.c
@@ -114,7 +114,7 @@ ASN1_TIME *ASN1_TIME_set(ASN1_TIME *s, time_t t)
 	return ASN1_GENERALIZEDTIME_set(s,t);
 	}
 
-int ASN1_TIME_check(ASN1_TIME *t)
+int ASN1_TIME_check(const ASN1_TIME *t)
 	{
 	if (t->type == V_ASN1_GENERALIZEDTIME)
 		return ASN1_GENERALIZEDTIME_check(t);
@@ -124,7 +124,8 @@ int ASN1_TIME_check(ASN1_TIME *t)
 	}
 
 /* Convert an ASN1_TIME structure to GeneralizedTime */
-ASN1_GENERALIZEDTIME *ASN1_TIME_to_generalizedtime(ASN1_TIME *t, ASN1_GENERALIZEDTIME **out)
+ASN1_GENERALIZEDTIME *ASN1_TIME_to_generalizedtime(const ASN1_TIME *t,
+						   ASN1_GENERALIZEDTIME **out)
 	{
 	ASN1_GENERALIZEDTIME *ret;
 	char *str;
diff --git a/crypto/asn1/a_utctm.c b/crypto/asn1/a_utctm.c
index dbb4a42c9..72088247b 100644
--- a/crypto/asn1/a_utctm.c
+++ b/crypto/asn1/a_utctm.c
@@ -112,7 +112,7 @@ err:
 
 #endif
 
-int ASN1_UTCTIME_check(ASN1_UTCTIME *d)
+int ASN1_UTCTIME_check(const ASN1_UTCTIME *d)
 	{
 	static int min[8]={ 0, 1, 1, 0, 0, 0, 0, 0};
 	static int max[8]={99,12,31,23,59,59,12,59};
diff --git a/crypto/asn1/asn1.h b/crypto/asn1/asn1.h
index 3414509f1..445b8363b 100644
--- a/crypto/asn1/asn1.h
+++ b/crypto/asn1/asn1.h
@@ -754,7 +754,7 @@ int ASN1_INTEGER_cmp(ASN1_INTEGER *x, ASN1_INTEGER *y);
 
 DECLARE_ASN1_FUNCTIONS(ASN1_ENUMERATED)
 
-int ASN1_UTCTIME_check(ASN1_UTCTIME *a);
+int ASN1_UTCTIME_check(const ASN1_UTCTIME *a);
 ASN1_UTCTIME *ASN1_UTCTIME_set(ASN1_UTCTIME *s,time_t t);
 int ASN1_UTCTIME_set_string(ASN1_UTCTIME *s, char *str); 
 int ASN1_UTCTIME_cmp_time_t(const ASN1_UTCTIME *s, time_t t);
@@ -762,7 +762,7 @@ int ASN1_UTCTIME_cmp_time_t(const ASN1_UTCTIME *s, time_t t);
 time_t ASN1_UTCTIME_get(const ASN1_UTCTIME *s);
 #endif
 
-int ASN1_GENERALIZEDTIME_check(ASN1_GENERALIZEDTIME *a);
+int ASN1_GENERALIZEDTIME_check(const ASN1_GENERALIZEDTIME *a);
 ASN1_GENERALIZEDTIME *ASN1_GENERALIZEDTIME_set(ASN1_GENERALIZEDTIME *s,time_t t);
 int ASN1_GENERALIZEDTIME_set_string(ASN1_GENERALIZEDTIME *s, char *str); 
 
@@ -793,8 +793,8 @@ DECLARE_ASN1_FUNCTIONS(ASN1_GENERALIZEDTIME)
 DECLARE_ASN1_FUNCTIONS(ASN1_TIME)
 
 ASN1_TIME *ASN1_TIME_set(ASN1_TIME *s,time_t t);
-int ASN1_TIME_check(ASN1_TIME *t);
-ASN1_GENERALIZEDTIME *ASN1_TIME_to_generalizedtime(ASN1_TIME *t, ASN1_GENERALIZEDTIME **out);
+int ASN1_TIME_check(const ASN1_TIME *t);
+ASN1_GENERALIZEDTIME *ASN1_TIME_to_generalizedtime(const ASN1_TIME *t, ASN1_GENERALIZEDTIME **out);
 
 int		i2d_ASN1_SET(STACK *a, unsigned char **pp,
 			int (*func)(), int ex_tag, int ex_class, int is_set);