diff --git a/i3lock.c b/i3lock.c
index ae1e884..8d4eb11 100644
--- a/i3lock.c
+++ b/i3lock.c
@@ -439,7 +439,7 @@ static int conv_callback(int num_msg, const struct pam_message **msg,
         return 1;
 
     /* PAM expects an array of responses, one for each message */
-    if ((*resp = calloc(num_msg, sizeof(struct pam_message))) == NULL) {
+    if ((*resp = calloc(num_msg, sizeof(struct pam_response))) == NULL) {
         perror("calloc");
         return 1;
     }