1 files changed, 1 insertions, 1 deletions

diff --git a/stack.h b/stack.h
index 6267f23..d3a4119 100644
--- a/stack.h
+++ b/stack.h
@@ -65,7 +65,7 @@ static inline Card stackPop(struct Stack *stack) {
 	return stack->cards[--stack->len];
 }
 
-static inline Card stackTop(struct Stack *stack) {
+static inline Card stackTop(const struct Stack *stack) {
 	if (!stack->len) return 0;
 	return stack->cards[stack->len - 1];
 }