diff --git a/lib/stack.c b/lib/stack.c
index 41b1ab9..2c7c688 100644
--- a/lib/stack.c
+++ b/lib/stack.c
@@ -81,10 +81,10 @@ void push(struct stack **stack, struct card *card) {
 
   if (card) {
     if (empty(*stack)) {
-      (*stack)->card = card;
+      (*stack)->card = duplicate_card(card);
     } else {
       allocate_stack(&new_stack);
-      new_stack->card = card;
+      new_stack->card = duplicate_card(card);
       new_stack->next = (*stack);
       *stack = new_stack;
     }
@@ -95,20 +95,23 @@ struct stack *pop(struct stack **stack) {
   struct stack *popped_entry = NULL;
 
   if(!empty(*stack)) {
-    popped_entry = *stack;
-    /* As what's considered an empty stack is an allocated and initialized
-     * stack structure, we make sure pop doesn't make '*stack' point to NULL
-     * when popping a stack with only 1 element. */
+    allocate_stack(&popped_entry);
+    initialize_stack(popped_entry);
+    popped_entry->card = duplicate_card((*stack)->card);
+    popped_entry->next = NULL;
     if (length(*stack) == 1) {
-      allocate_stack(stack);
-      initialize_stack(*stack);
-      set_frame((*stack)->card->frame,
-                (*stack)->card->frame->start_y,
-                (*stack)->card->frame->start_x);
+      /* An empty stack is a stack with a blank top card
+       * and with stack->next == NULL. */
+      set_card((*stack)->card,
+               NO_VALUE,
+               NO_SUIT,
+               NO_FACE,
+               (*stack)->card->frame->start_y,
+               (*stack)->card->frame->start_x);
+      (*stack)->next = NULL;
     } else {
       *stack = (*stack)->next;
     }
-    popped_entry->next = NULL;
   }
 
   return(popped_entry);
diff --git a/test/stack_test.c b/test/stack_test.c
index a8eb6d6..154287a 100644
--- a/test/stack_test.c
+++ b/test/stack_test.c
@@ -102,7 +102,7 @@ void test_push_on_empty_stack() {
   initialize_stack(stack);
   push(&stack, card);
 
-  assert(stack->card == card);
+  assert(cards_equal(stack->card, card));
   assert(!stack->next);
 
   free_stack(stack);
@@ -126,8 +126,8 @@ void test_push_on_non_empty_stack() {
   push(&stack, card_0);
   push(&stack, card_1);
 
-  assert(stack->card == card_1);
-  assert(stack->next->card == card_0);
+  assert(cards_equal(stack->card, card_1));
+  assert(cards_equal(stack->next->card, card_0));
   assert(!stack->next->next);
 
   free_stack(stack);
@@ -143,8 +143,8 @@ void test_push_null_on_empty_stack() {
   old_stack = stack;
   push(&stack, NULL);
 
-  assert(stack->card == old_stack->card);
-  assert(stack->next == NULL);
+  assert(cards_equal(stack->card, old_stack->card));
+  assert(!stack->next);
 
   free_stack(stack);
 
@@ -161,11 +161,11 @@ void test_push_null_on_non_empty_stack() {
 
   allocate_stack(&stack);
   initialize_stack(stack);
-  old_stack = stack;
+  old_stack = duplicate_stack(stack);
   push(&stack, NULL);
 
-  assert(stack->card == old_stack->card);
-  assert(stack->next == old_stack->next);
+  assert(cards_equal(stack->card, old_stack->card));
+  assert(stacks_equal(stack->next, old_stack->next));
 
   free_stack(stack);
 
@@ -203,7 +203,7 @@ void test_pop_on_stack_with_one_element() {
   popped_entry = pop(&stack);
 
   assert(empty(stack));
-  assert(popped_entry->card == card);
+  assert(cards_equal(popped_entry->card, card));
   assert(!popped_entry->next);
 
   free_stack(stack);
@@ -228,7 +228,7 @@ void test_pop_on_stack_with_more_than_one_element() {
 
   assert(length(stack) == 2);
   assert(stack == old_stack_next);
-  assert(popped_entry->card == card[2]);
+  assert(cards_equal(popped_entry->card, card[2]));
   assert(!popped_entry->next);
 
   free_stack(stack);