diff --git a/bintree.c b/bintree.c
index 0c5b453..5cf82a9 100644
--- a/bintree.c
+++ b/bintree.c
@@ -1,4 +1,4 @@
-t #include <string.h>
+#include <string.h>
 #include "stack.h"
 #include "bintree.h"
 
diff --git a/stack.c b/stack.c
index dbda947..930fc2d 100644
--- a/stack.c
+++ b/stack.c
@@ -69,11 +69,15 @@ StackNode *pop(StackNode *stack) {
 void *top(StackNode *stack) { return stack != NULL ? stack->data : NULL; }
 
 // Clears stack and releases all memory.
-void *clearStack(StackNode *stack) {
+void clearStack(StackNode *stack) {
 
   while (stack != NULL) {
 
     StackNode *next = stack->next;
+    stack->data = NULL;
+    stack->prev = NULL;
+    stack->next = NULL;
+    
     free(stack);
     stack = next;
   }
diff --git a/stack.h b/stack.h
index fb1cd04..c7bbef4 100644
--- a/stack.h
+++ b/stack.h
@@ -14,7 +14,7 @@ typedef struct StackNode {
   void *data;
   struct StackNode *next;
   struct StackNode *prev;
-  
+
 } StackNode;
 
 StackNode *createNode(void *data);
@@ -30,6 +30,6 @@ StackNode *pop(StackNode *stack);
 void *top(StackNode *stack);
 
 // Clears stack and releases all memory.
-StackNode *clearStack(StackNode *stack);
+void clearStack(StackNode *stack);
 
 #endif
diff --git a/test_stack.c b/test_stack.c
index 52ff263..2ad909f 100644
--- a/test_stack.c
+++ b/test_stack.c
@@ -36,7 +36,7 @@ void test_clearStack(void) {
     testStack = push(testStack, &testInts[i]);
   }
 
-  testStack = clearStack(testStack);
+  clearStack(testStack);
   TEST_ASSERT_NULL(testStack);
 }