1 files changed, 2 insertions, 2 deletions

diff --git a/src/lib/libcrypto/stack/stack.h b/src/lib/libcrypto/stack/stack.h
index 0f825cc0c4..a615d9b4c9 100644
--- a/src/lib/libcrypto/stack/stack.h
+++ b/src/lib/libcrypto/stack/stack.h
@@ -76,8 +76,8 @@ typedef struct stack_st
 
 #define sk_new_null()   sk_new(NULL)
 
-#define M_sk_num(sk)            ((sk)->num)
-#define M_sk_value(sk,n)        ((sk)->data[n])
+#define M_sk_num(sk)            ((sk) ? (sk)->num:-1)
+#define M_sk_value(sk,n)        ((sk) ? (sk)->data[n] : NULL)
 
 int sk_num(STACK *);
 char *sk_value(STACK *, int);