diff --git a/Makefile b/Makefile
index 9a1574b..4d696f8 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,4 @@
 CFLAGS += -std=c11 -g -Wall -Wextra -ftrapv -Wshadow -Wundef -Wcast-align -Wunreachable-code -O1
-
 SRC = src/*.c
 TEST_SRC = test/*.c
 
diff --git a/include/mem_pool.h b/include/mem_pool.h
index 1f94e73..8166b0c 100644
--- a/include/mem_pool.h
+++ b/include/mem_pool.h
@@ -11,7 +11,8 @@
  * Pass this as the second argument to pool_variable_init if you wan to skip
  * best fit checks
  */
-#define MEM_POOL_NO_BEST_FIT -1
+/* #define MEM_POOL_NO_BEST_FIT 101 */
+static const uint16_t MEM_POOL_NO_BEST_FIT = 101;
 
 
 typedef struct FixedMemPool FixedMemPool;
@@ -68,8 +69,9 @@ MemPoolError pool_fixed_destroy(FixedMemPool *pool);
 /**
  * grow_size deremines the size of a new buffer required from malloc when no more free (fitting) space left
  * tolerance_percent is the maximum difference in percentage when looking for best fitting free blocks
+ * if not reuqired, use MEM_POOL_NO_BEST_FIT
  */
-MemPoolError pool_variable_init(VariableMemPool **pool, size_t grow_size, int16_t tolerance_percent);
+MemPoolError pool_variable_init(VariableMemPool **pool, size_t grow_size, uint16_t tolerance_percent);
 
 MemPoolError pool_variable_alloc(VariableMemPool *pool, size_t size, void **ptr);
 
diff --git a/src/internals.h b/src/internals.h
index df435df..85beeea 100644
--- a/src/internals.h
+++ b/src/internals.h
@@ -46,10 +46,10 @@
 typedef struct Buffer Buffer;
 
 struct Buffer {
-    void *start;
-    void *prev_ptr;
-    void *curr_ptr; /* This is only tracked for variadic blocks */
-    void *end;
+    char *start;
+    char *prev_ptr;
+    char *curr_ptr; /* This is only tracked for variadic blocks */
+    char *end;
     Buffer *next;
 };
 
@@ -79,7 +79,7 @@ static inline bool buffer_has_space(Buffer *buff, size_t size)
     return (char *)buff->end - (char *)buff->curr_ptr >= (long)size;
 }
 
-static inline bool buffer_has(Buffer *buff, void *ptr)
+static inline bool buffer_has(Buffer *buff, char *ptr)
 {
     return ptr >= buff->start && ptr <= buff->end;
 }
diff --git a/src/variable.c b/src/variable.c
index 24499d7..63ae631 100644
--- a/src/variable.c
+++ b/src/variable.c
@@ -10,7 +10,7 @@ struct SizedBlock {
 struct VariableMemPool {
     size_t buff_size;
     size_t header_size;
-    int16_t tolerance_percent;
+    uint16_t tolerance_percent;
     Buffer *buff_head;
     Buffer *buff_last;
     SizedBlock *block_head;
@@ -18,13 +18,14 @@ struct VariableMemPool {
 };
 
 
-MemPoolError pool_variable_init(VariableMemPool **pool, size_t grow_size, int16_t tolerance_percent)
+MemPoolError pool_variable_init(VariableMemPool **pool, size_t grow_size, uint16_t tolerance_percent)
 {
     *pool = malloc(sizeof(VariableMemPool));
     if (!*pool) {
         return MEM_POOL_ERR_MALLOC;
     }
-    (*pool)->tolerance_percent = max(MEM_POOL_NO_BEST_FIT, tolerance_percent);
+    /* (*pool)->tolerance_percent = tolerance_percent <= MEM_POOL_NO_BEST_FIT ? MEM_POOL_NO_BEST_FIT : tolerance_percent; */
+    (*pool)->tolerance_percent = tolerance_percent >= MEM_POOL_NO_BEST_FIT ? MEM_POOL_NO_BEST_FIT : tolerance_percent;
     (*pool)->header_size = mem_align(sizeof(Header));
     (*pool)->buff_size = grow_size;
     (*pool)->buff_head = buffer_new(grow_size);
@@ -43,9 +44,9 @@ MemPoolError pool_variable_init(VariableMemPool **pool, size_t grow_size, int16_
 
 static void *from_buffer(Buffer *buff, size_t header_size, size_t block_size)
 {
-    Header *header = buff->curr_ptr;
+    Header *header = (void *) buff->curr_ptr;
     header->size = block_size;
-    header->prev_in_buff = buff->prev_ptr;
+    header->prev_in_buff = (void *) buff->prev_ptr;
 
     buff->prev_ptr = buff->curr_ptr;
     buff->curr_ptr += (header_size + block_size);
@@ -56,13 +57,14 @@ static void *from_buffer(Buffer *buff, size_t header_size, size_t block_size)
 static void *best_fit_from_free_list(VariableMemPool *pool, size_t required_size)
 {
     SizedBlock **curr = &pool->block_head;
-    int64_t block_size, diff;
-    int16_t diff_percent;
+    size_t block_size;
+    long diff;
+    size_t diff_percent;
 
     while (*curr) {
         block_size = (*curr)->header.size;
-        diff = labs(block_size - (long)required_size);
-        diff_percent = (diff * 100) / ((block_size + required_size) / 2);
+        diff = labs((long) block_size - (long) required_size);
+        diff_percent = ((size_t) diff * 100) / ((block_size + required_size) / 2);
 
         if (MEM_POOL_NO_BEST_FIT == pool->tolerance_percent || diff_percent <= pool->tolerance_percent) {
             SizedBlock *block = *curr;
@@ -132,7 +134,7 @@ static SizedBlock *append(SizedBlock *to, SizedBlock *from, size_t header_size)
 
 static SizedBlock *merge_next_free_blocks(VariableMemPool *pool, Buffer *buff, SizedBlock *block)
 {
-    SizedBlock *next = NULL;
+    void *next = NULL;
 
     while (1) {
         next = (SizedBlock *)((char *)block + block->header.size + pool->header_size);
diff --git a/test/minunit.h b/test/minunit/minunit.h
similarity index 100%
rename from test/minunit.h
rename to test/minunit/minunit.h