@@ -18,10 +18,11 @@
 #import "OFMessagePackExtension.h"
 #import "OFData.h"
 #import "OFString.h"
 
 #import "OFInvalidArgumentException.h"
+#import "OFOutOfRangeException.h"
 
 @implementation OFMessagePackExtension
 @synthesize type = _type, data = _data;
 
 + (instancetype)extensionWithType: (int8_t)type data: (OFData *)data
@@ -98,11 +99,11 @@
 
 		prefix = 0xD8;
 		[ret addItem: &prefix];
 
 		[ret addItem: &_type];
-	} else if (count < 0x100) {
+	} else if (count <= UINT8_MAX) {
 		uint8_t length;
 
 		ret = [OFMutableData dataWithCapacity: count + 3];
 
 		prefix = 0xC7;
@@ -110,11 +111,11 @@
 
 		length = (uint8_t)count;
 		[ret addItem: &length];
 
 		[ret addItem: &_type];
-	} else if (count < 0x10000) {
+	} else if (count <= UINT16_MAX) {
 		uint16_t length;
 
 		ret = [OFMutableData dataWithCapacity: count + 4];
 
 		prefix = 0xC8;
@@ -122,11 +123,11 @@
 
 		length = OFToBigEndian16((uint16_t)count);
 		[ret addItems: &length count: 2];
 
 		[ret addItem: &_type];
-	} else {
+	} else if (count <= UINT32_MAX) {
 		uint32_t length;
 
 		ret = [OFMutableData dataWithCapacity: count + 6];
 
 		prefix = 0xC9;
@@ -134,11 +135,12 @@
 
 		length = OFToBigEndian32((uint32_t)count);
 		[ret addItems: &length count: 4];
 
 		[ret addItem: &_type];
-	}
+	} else
+		@throw [OFOutOfRangeException exception];
 
 	[ret addItems: _data.items count: _data.count];
 	[ret makeImmutable];
 
 	return ret;