Index: src/OFDate.m
==================================================================
--- src/OFDate.m
+++ src/OFDate.m
@@ -366,13 +366,13 @@
 	uint32_t hash;
 	union {
 		double d;
 		uint8_t b[sizeof(double)];
 	} d;
-	uint8_t i;
+	uint_fast8_t i;
 
-	d.d = OF_BSWAP_DOUBLE_IF_LE(seconds);
+	d.d = OF_BSWAP_DOUBLE_IF_BE(seconds);
 
 	OF_HASH_INIT(hash);
 
 	for (i = 0; i < sizeof(double); i++)
 		OF_HASH_ADD(hash, d.b[i]);

Index: src/OFNumber.m
==================================================================
--- src/OFNumber.m
+++ src/OFNumber.m
@@ -1038,49 +1038,66 @@
 	}
 }
 
 - (uint32_t)hash
 {
+	of_number_type_t type_ = type;
 	uint32_t hash;
-	uint8_t i;
-
-	switch (type) {
-	case OF_NUMBER_FLOAT:;
-		union {
-			float f;
-			uint8_t b[sizeof(float)];
-		} f;
-
-		f.f = OF_BSWAP_FLOAT_IF_LE(value.float_);
-
-		OF_HASH_INIT(hash);
-
-		for (i = 0; i < sizeof(float); i++)
-			OF_HASH_ADD(hash, f.b[i]);
-
-		OF_HASH_FINALIZE(hash);
-
-		return hash;
-	case OF_NUMBER_DOUBLE:;
+
+	/* Do we really need signed to represent this number? */
+	if (type_ & OF_NUMBER_SIGNED && [self intMaxValue] >= 0)
+		type_ &= ~OF_NUMBER_SIGNED;
+
+	/* Do we really need floating point to represent this number? */
+	if (type_ & OF_NUMBER_FLOAT) {
+		double v = [self doubleValue];
+
+		if (v < 0) {
+			if (v == [self intMaxValue]) {
+				type_ &= ~OF_NUMBER_FLOAT;
+				type_ |= OF_NUMBER_SIGNED;
+			}
+		} else {
+			if (v == [self uIntMaxValue])
+				type_ &= ~OF_NUMBER_FLOAT;
+		}
+	}
+
+	OF_HASH_INIT(hash);
+
+	if (type_ & OF_NUMBER_FLOAT) {
 		union {
 			double d;
 			uint8_t b[sizeof(double)];
 		} d;
-
-		d.d = OF_BSWAP_DOUBLE_IF_LE(value.double_);
+		uint_fast8_t i;
 
-		OF_HASH_INIT(hash);
+		d.d = OF_BSWAP_DOUBLE_IF_BE([self doubleValue]);
 
 		for (i = 0; i < sizeof(double); i++)
 			OF_HASH_ADD(hash, d.b[i]);
+	} else if (type_ & OF_NUMBER_SIGNED) {
+		intmax_t v = [self intMaxValue] * -1;
+
+		while (v != 0) {
+			OF_HASH_ADD(hash, v & 0xFF);
+			v >>= 8;
+		}
 
-		OF_HASH_FINALIZE(hash);
+		OF_HASH_ADD(hash, 1);
+	} else {
+		uintmax_t v = [self uIntMaxValue];
 
-		return hash;
-	default:
-		return [self uInt32Value];
+		while (v != 0) {
+			OF_HASH_ADD(hash, v & 0xFF);
+			v >>= 8;
+		}
 	}
+
+	OF_HASH_FINALIZE(hash);
+
+	return hash;
 }
 
 - (OFNumber*)numberByAddingNumber: (OFNumber*)num
 {
 	CALCULATE(+, num)

Index: src/OFObject.m
==================================================================
--- src/OFObject.m
+++ src/OFObject.m
@@ -842,16 +842,30 @@
 }
 
 - (uint32_t)hash
 {
 	/* Classes containing data should reimplement this! */
-	return (uint32_t)(uintptr_t)self;
+
+	uintptr_t ptr = (uintptr_t)self;
+	uint32_t hash;
+
+	OF_HASH_INIT(hash);
+
+	while (ptr != 0) {
+		OF_HASH_ADD(hash, ptr & 0xFF);
+		ptr <<= 8;
+	}
+
+	OF_HASH_FINALIZE(hash);
+
+	return hash;
 }
 
 - (OFString*)description
 {
 	/* Classes containing data should reimplement this! */
+
 	return [OFString stringWithFormat: @"<%@: %p>", [self className], self];
 }
 
 - (void*)allocMemoryWithSize: (size_t)size
 {

Index: src/macros.h
==================================================================
--- src/macros.h
+++ src/macros.h
@@ -325,15 +325,15 @@
 #define OF_ROL(value, bits)						\
 	(((value) << ((bits) % (sizeof(value) * 8))) |			\
 	(value) >> (sizeof(value) * 8 - ((bits) % (sizeof(value) * 8))))
 
 #define OF_HASH_INIT(hash) hash = of_hash_seed
-#define OF_HASH_ADD(hash, byte)		\
-	{				\
-		hash += (uint8_t)byte;	\
-		hash += (hash << 10);	\
-		hash ^= (hash >> 6);	\
+#define OF_HASH_ADD(hash, byte)			\
+	{					\
+		hash += (uint8_t)(byte);	\
+		hash += (hash << 10);		\
+		hash ^= (hash >> 6);		\
 	}
 #define OF_HASH_FINALIZE(hash)		\
 	{				\
 		hash += (hash << 3);	\
 		hash ^= (hash >> 11);	\

Index: tests/OFNumberTests.m
==================================================================
--- tests/OFNumberTests.m
+++ tests/OFNumberTests.m
@@ -34,13 +34,13 @@
 	    (num = [OFNumber numberWithIntMax: 123456789]))
 
 	TEST(@"-[isEqual:]",
 	    [num isEqual: [OFNumber numberWithUInt32: 123456789]])
 
-	TEST(@"-[hash]", [num hash] == 123456789)
+	TEST(@"-[hash]", [num hash] == 0x82D8BC42)
 
-	TEST(@"-[asDouble]", [num doubleValue] == 123456789.L)
+	TEST(@"-[doubleValue]", [num doubleValue] == 123456789.L)
 
 	TEST(@"-[numberByDecreasing]",
 	    [[num numberByDecreasing]
 	    isEqual: [OFNumber numberWithInt32: 123456788]])
 

Index: tests/OFStringTests.m
==================================================================
--- tests/OFStringTests.m
+++ tests/OFStringTests.m
@@ -118,11 +118,11 @@
 	    R([s[1] appendUTF8String: "1𝄞"]) && R([s[1] appendString: @"3"]) &&
 	    R([s[0] appendString: s[1]]) && [s[0] isEqual: @"täs€1𝄞3"])
 
 	TEST(@"-[length]", [s[0] length] == 7)
 	TEST(@"-[UTF8StringLength]", [s[0] UTF8StringLength] == 13)
-	TEST(@"-[hash]", [s[0] hash] == 0x2E623BD1)
+	TEST(@"-[hash]", [s[0] hash] == 0x705583C0)
 
 	TEST(@"-[characterAtIndex:]", [s[0] characterAtIndex: 0] == 't' &&
 	    [s[0] characterAtIndex: 1] == 0xE4 &&
 	    [s[0] characterAtIndex: 3] == 0x20AC &&
 	    [s[0] characterAtIndex: 5] == 0x1D11E)

Index: tests/serialization.xml
==================================================================
--- tests/serialization.xml
+++ tests/serialization.xml
@@ -1,34 +1,15 @@
 <?xml version='1.0' encoding='UTF-8'?>
 <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'>40934a456d5cfaad</OFNumber>
-        <OFMutableString>asd</OFMutableString>
-        <OFDate>40934a456d5cfaad</OFDate>
-      </OFArray>
-    </key>
-    <object>
-      <OFString>Hello</OFString>
-    </object>
-    <key>
       <OFString>Blub</OFString>
     </key>
     <object>
       <OFString>B&quot;la</OFString>
     </object>
     <key>
-      <OFDataArray>MDEyMzQ1Njc4OTo7PEFCQ0RFRkdISklLTE1OT1BRUlNUVVZXWFla</OFDataArray>
-    </key>
-    <object>
-      <OFString>data</OFString>
-    </object>
-    <key>
       <OFList>
         <OFString>Hello</OFString>
         <OFString>Wo&#xD;ld!
 How are you?</OFString>
         <OFURL>https://webkeks.org/</OFURL>
@@ -55,7 +36,26 @@
       </OFList>
     </key>
     <object>
       <OFString>list</OFString>
     </object>
+    <key>
+      <OFDataArray>MDEyMzQ1Njc4OTo7PEFCQ0RFRkdISklLTE1OT1BRUlNUVVZXWFla</OFDataArray>
+    </key>
+    <object>
+      <OFString>data</OFString>
+    </object>
+    <key>
+      <OFArray>
+        <OFString>Qu&quot;xbar
+test</OFString>
+        <OFNumber type='signed'>1234</OFNumber>
+        <OFNumber type='double'>40934a456d5cfaad</OFNumber>
+        <OFMutableString>asd</OFMutableString>
+        <OFDate>40934a456d5cfaad</OFDate>
+      </OFArray>
+    </key>
+    <object>
+      <OFString>Hello</OFString>
+    </object>
   </OFMutableDictionary>
 </serialization>