Index: src/OFBigDataArray.m
==================================================================
--- src/OFBigDataArray.m
+++ src/OFBigDataArray.m
@@ -22,10 +22,12 @@
 #import "OFSystemInfo.h"
 
 #import "OFInvalidArgumentException.h"
 #import "OFOutOfMemoryException.h"
 #import "OFOutOfRangeException.h"
+
+#import "macros.h"
 
 @implementation OFBigDataArray
 - init
 {
 	return [self initWithItemSize: 1
@@ -42,23 +44,23 @@
 	  capacity: (size_t)capacity
 {
 	self = [super init];
 
 	@try {
-		size_t size, lastPageByte;
+		size_t size, pageSize;
 
 		if (itemSize == 0)
 			@throw [OFInvalidArgumentException exception];
 
 		if (capacity > SIZE_MAX / itemSize)
 			@throw [OFOutOfRangeException exception];
 
-		lastPageByte = [OFSystemInfo pageSize] - 1;
-		size = (capacity * itemSize + lastPageByte) & ~lastPageByte;
+		pageSize = [OFSystemInfo pageSize];
+		size = OF_ROUND_UP_POW2(pageSize, capacity * itemSize);
 
 		if (size == 0)
-			size = lastPageByte + 1;
+			size = pageSize;
 
 		_items = [self allocMemoryWithSize: size];
 
 		_itemSize = itemSize;
 		_capacity = size / itemSize;
@@ -75,15 +77,14 @@
 {
 	if (SIZE_MAX - _count < 1 || _count + 1 > SIZE_MAX / _itemSize)
 		@throw [OFOutOfRangeException exception];
 
 	if (_count + 1 > _capacity) {
-		size_t size, lastPageByte;
+		size_t size, pageSize;
 
-		lastPageByte = [OFSystemInfo pageSize] - 1;
-		size = ((_count + 1) * _itemSize + lastPageByte) &
-		    ~lastPageByte;
+		pageSize = [OFSystemInfo pageSize];
+		size = OF_ROUND_UP_POW2(pageSize, (_count + 1) * _itemSize);
 
 		_items = [self resizeMemory: _items
 				       size: size];
 
 		_capacity = size / _itemSize;
@@ -100,15 +101,14 @@
 {
 	if (count > SIZE_MAX - _count || _count + count > SIZE_MAX / _itemSize)
 		@throw [OFOutOfRangeException exception];
 
 	if (_count + count > _capacity) {
-		size_t size, lastPageByte;
+		size_t size, pageSize;
 
-		lastPageByte = [OFSystemInfo pageSize] - 1;
-		size = ((_count + count) * _itemSize + lastPageByte) &
-		    ~lastPageByte;
+		pageSize = [OFSystemInfo pageSize];
+		size = OF_ROUND_UP_POW2(pageSize, (_count + count) * _itemSize);
 
 		_items = [self resizeMemory: _items
 				       size: size];
 
 		_capacity = size / _itemSize;
@@ -127,15 +127,14 @@
 	if (count > SIZE_MAX - _count || index > _count ||
 	    _count + count > SIZE_MAX / _itemSize)
 		@throw [OFOutOfRangeException exception];
 
 	if (_count + count > _capacity) {
-		size_t size, lastPageByte;
+		size_t size, pageSize;
 
-		lastPageByte = [OFSystemInfo pageSize] - 1;
-		size = ((_count + count) * _itemSize + lastPageByte) &
-		    ~lastPageByte;
+		pageSize = [OFSystemInfo pageSize];
+		size = OF_ROUND_UP_POW2(pageSize, (_count + count) * _itemSize);
 
 		_items = [self resizeMemory: _items
 				       size: size];
 
 		_capacity = size / _itemSize;
@@ -149,11 +148,11 @@
 	_count += count;
 }
 
 - (void)removeItemsInRange: (of_range_t)range
 {
-	size_t lastPageByte, size;
+	size_t pageSize, size;
 
 	if (range.length > SIZE_MAX - range.location ||
 	    range.location + range.length > _count)
 		@throw [OFOutOfRangeException exception];
 
@@ -160,14 +159,14 @@
 	memmove(_items + range.location * _itemSize,
 	    _items + (range.location + range.length) * _itemSize,
 	    (_count - range.location - range.length) * _itemSize);
 
 	_count -= range.length;
-	lastPageByte = [OFSystemInfo pageSize] - 1;
-	size = (_count * _itemSize + lastPageByte) & ~lastPageByte;
+	pageSize = [OFSystemInfo pageSize];
+	size = OF_ROUND_UP_POW2(pageSize, _count * _itemSize);
 
-	if (_size != size && size > lastPageByte) {
+	if (_size != size && size >= pageSize) {
 		@try {
 			_items = [self resizeMemory: _items
 					       size: size];
 			_capacity = size / _itemSize;
 			_size = size;
@@ -177,20 +176,20 @@
 	}
 }
 
 - (void)removeLastItem
 {
-	size_t lastPageByte, size;
+	size_t pageSize, size;
 
 	if (_count == 0)
 		return;
 
 	_count--;
-	lastPageByte = [OFSystemInfo pageSize] - 1;
-	size = (_count * _itemSize + lastPageByte) & ~lastPageByte;
+	pageSize = [OFSystemInfo pageSize];
+	size = OF_ROUND_UP_POW2(pageSize, _count * _itemSize);
 
-	if (_size != size && size > lastPageByte) {
+	if (_size != size && size >= pageSize) {
 		@try {
 			_items = [self resizeMemory: _items
 					       size: size];
 			_capacity = size / _itemSize;
 			_size = size;

Index: src/macros.h
==================================================================
--- src/macros.h
+++ src/macros.h
@@ -355,10 +355,12 @@
 	(((value) << ((bits) % (sizeof(value) * 8))) |			   \
 	((value) >> (sizeof(value) * 8 - ((bits) % (sizeof(value) * 8)))))
 #define OF_ROR(value, bits)						   \
 	(((value) >> ((bits) % (sizeof(value) * 8))) |			   \
 	((value) << (sizeof(value) * 8 - ((bits) % (sizeof(value) * 8)))))
+
+#define OF_ROUND_UP_POW2(pow2, value) (((value) + (pow2) - 1) & ~((pow2) - 1))
 
 #define OF_HASH_INIT(hash) hash = of_hash_seed;
 #define OF_HASH_ADD(hash, byte)			\
 	{					\
 		hash += (uint8_t)(byte);	\