diff --git a/src/win_utils.c b/src/win_utils.c
index 45f70d4a..2b9803fd 100644
--- a/src/win_utils.c
+++ b/src/win_utils.c
@@ -248,8 +248,8 @@ void snapshot_stack_list(int free_only, double allowed_age) {
 	}
 
 	last_snap = now;
-	if (num > stack_list_len + blackouts) {
-		int n = 2*num;
+	if (num + blackouts > stack_list_len) {
+		int n = 2 * (num + blackouts);
 		free(stack_list);
 		stack_list = (winattr_t *) malloc(n*sizeof(winattr_t));
 		stack_list_len = n;
diff --git a/src/xrecord.c b/src/xrecord.c
index a657ce80..4bc119c1 100644
--- a/src/xrecord.c
+++ b/src/xrecord.c
@@ -961,7 +961,7 @@ if (db > 1) fprintf(stderr, "record_CW-%d\n", k++);
 	data = (char *)req;
 	data += sz_xConfigureWindowReq;
 
-	for (i=0; i<req->length; i++) {
+	for (i = 0; i < req->length - sz_xConfigureWindowReq / 4 && i < 4; i++) {
 		unsigned int v;
 		/*
 		 * We use unsigned int for the values.  There were