diff --git a/doc/man3/BN_CTX_start.pod b/doc/man3/BN_CTX_start.pod
index bf3a8b59ad..d4780fe9cd 100644
--- a/doc/man3/BN_CTX_start.pod
+++ b/doc/man3/BN_CTX_start.pod
@@ -27,6 +27,7 @@ calls must be made before calling any other functions that use the
 B<ctx> as an argument.
 
 Finally, BN_CTX_end() must be called before returning from the function.
+If B<ctx> is NULL, nothing is done.
 When BN_CTX_end() is called, the B<BIGNUM> pointers obtained from
 BN_CTX_get() become invalid.
 
diff --git a/doc/man3/BN_new.pod b/doc/man3/BN_new.pod
index e3800b82b7..e7269e0176 100644
--- a/doc/man3/BN_new.pod
+++ b/doc/man3/BN_new.pod
@@ -27,6 +27,7 @@ OPENSSL_secure_malloc(3) is used to store the value.
 BN_clear() is used to destroy sensitive data such as keys when they
 are no longer needed. It erases the memory used by B<a> and sets it
 to the value 0.
+If B<a> is NULL, nothing is done.
 
 BN_free() frees the components of the B<BIGNUM>, and if it was created
 by BN_new(), also the structure itself. BN_clear_free() additionally