Index: src/OFDate.m
==================================================================
--- src/OFDate.m
+++ src/OFDate.m
@@ -321,18 +321,23 @@
 {
 	self = [super init];
 
 	@try {
 		OFAutoreleasePool *pool = [[OFAutoreleasePool alloc] init];
+		union {
+			double d;
+			uint64_t u;
+		} d;
 
 		if (![[element name] isEqual: [self className]] ||
 		    ![[element namespace] isEqual: OF_SERIALIZATION_NS])
 			@throw [OFInvalidArgumentException
 			    exceptionWithClass: [self class]
 				      selector: _cmd];
 
-		seconds = [element doubleValue];
+		d.u = (uint64_t)[element hexadecimalValue];
+		seconds = of_bswap_double_if_le(d.d);
 
 		[pool release];
 	} @catch (id e) {
 		[self release];
 		@throw e;
@@ -408,14 +413,21 @@
 
 - (OFXMLElement*)XMLElementBySerializing
 {
 	OFAutoreleasePool *pool = [[OFAutoreleasePool alloc] init];
 	OFXMLElement *element;
+	union {
+		double d;
+		uint64_t u;
+	} d;
 
 	element = [OFXMLElement elementWithName: [self className]
 				      namespace: OF_SERIALIZATION_NS];
-	[element setStringValue: [OFString stringWithFormat: @"%la", seconds]];
+
+	d.d = of_bswap_double_if_le(seconds);
+	[element setStringValue:
+	    [OFString stringWithFormat: @"%016" PRIx64, d.u]];
 
 	[element retain];
 	[pool release];
 	[element autorelease];
 

Index: src/OFNumber.m
==================================================================
--- src/OFNumber.m
+++ src/OFNumber.m
@@ -750,15 +750,29 @@
 			value.uintmax = [element decimalValue];
 		} else if ([typeString isEqual: @"signed"]) {
 			type = OF_NUMBER_INTMAX;
 			value.intmax = [element decimalValue];
 		} else if ([typeString isEqual: @"float"]) {
+			union {
+				float f;
+				uint32_t u;
+			} f;
+
+			f.u = (uint32_t)[element hexadecimalValue];
+
 			type = OF_NUMBER_FLOAT;
-			value.float_ = [element floatValue];
+			value.float_ = of_bswap_float_if_le(f.f);
 		} else if ([typeString isEqual: @"double"]) {
+			union {
+				double d;
+				uint64_t u;
+			} d;
+
+			d.u = (uint64_t)[element hexadecimalValue];
+
 			type = OF_NUMBER_DOUBLE;
-			value.double_ = [element doubleValue];
+			value.double_ = of_bswap_double_if_le(d.d);
 		} else
 			@throw [OFInvalidArgumentException
 			    exceptionWithClass: [self class]
 				      selector: _cmd];
 
@@ -1237,21 +1251,35 @@
 	case OF_NUMBER_INTPTR:;
 		[element addAttributeWithName: @"type"
 				  stringValue: @"signed"];
 		break;
 	case OF_NUMBER_FLOAT:;
+		union {
+			float f;
+			uint32_t u;
+		} f;
+
+		f.f = of_bswap_float_if_le(value.float_);
+
 		[element addAttributeWithName: @"type"
 				  stringValue: @"float"];
 		[element setStringValue:
-		    [OFString stringWithFormat: @"%a", value.float_]];
+		    [OFString stringWithFormat: @"%08" PRIx32, f.u]];
 
 		break;
 	case OF_NUMBER_DOUBLE:;
+		union {
+			double d;
+			uint64_t u;
+		} d;
+
+		d.d = of_bswap_double_if_le(value.double_);
+
 		[element addAttributeWithName: @"type"
 				  stringValue: @"double"];
 		[element setStringValue:
-		    [OFString stringWithFormat: @"%la", value.double_]];
+		    [OFString stringWithFormat: @"%016" PRIx64, d.u]];
 
 		break;
 	default:
 		@throw [OFInvalidFormatException
 		    exceptionWithClass: [self class]];

Index: src/OFObject+Serialization.m
==================================================================
--- src/OFObject+Serialization.m
+++ src/OFObject+Serialization.m
@@ -44,11 +44,11 @@
 	element = [(id)self XMLElementBySerializing];
 
 	root = [OFXMLElement elementWithName: @"serialization"
 				   namespace: OF_SERIALIZATION_NS];
 	[root addAttributeWithName: @"version"
-		       stringValue: @"0"];
+		       stringValue: @"1"];
 	[root addChild: element];
 
 	ret = [@"<?xml version='1.0' encoding='UTF-8'?>\n"
 	    stringByAppendingString: [root XMLStringWithIndentation: 2]];
 

Index: src/OFString+Serialization.m
==================================================================
--- src/OFString+Serialization.m
+++ src/OFString+Serialization.m
@@ -55,11 +55,11 @@
 	if (version == nil)
 		@throw [OFInvalidArgumentException
 		    exceptionWithClass: [self class]
 			      selector: _cmd];
 
-	if ([version decimalValue] > 0)
+	if ([version decimalValue] != 1)
 		@throw [OFUnsupportedVersionException
 		    exceptionWithClass: [self class]
 			       version: version];
 
 	elements = [root elementsForNamespace: OF_SERIALIZATION_NS];

Index: src/asprintf.m
==================================================================
--- src/asprintf.m
+++ src/asprintf.m
@@ -18,14 +18,10 @@
 
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdarg.h>
 
-#ifdef __MINGW32__
-# define vsnprintf _vsnprintf
-#endif
-
 int
 vasprintf(char **cString, const char *format, va_list arguments)
 {
 	int length;
 

Index: tests/serialization.xml
==================================================================
--- tests/serialization.xml
+++ tests/serialization.xml
@@ -1,16 +1,16 @@
 <?xml version='1.0' encoding='UTF-8'?>
-<serialization xmlns='https://webkeks.org/objfw/serialization' version='0'>
+<serialization xmlns='https://webkeks.org/objfw/serialization' version='1'>
   <OFMutableDictionary>
     <key>
       <OFArray>
         <OFString>Qu&quot;xbar
 test</OFString>
         <OFNumber type='signed'>1234</OFNumber>
-        <OFNumber type='double'>0x1.34a456d5cfaadp+10</OFNumber>
+        <OFNumber type='double'>adfa5c6d454a9340</OFNumber>
         <OFMutableString>asd</OFMutableString>
-        <OFDate>0x1.34a456d5cfaadp+10</OFDate>
+        <OFDate>adfa5c6d454a9340</OFDate>
       </OFArray>
     </key>
     <object>
       <OFString>Hello</OFString>
     </object>