Index: src/OFArray.m
==================================================================
--- src/OFArray.m
+++ src/OFArray.m
@@ -163,10 +163,23 @@
 			return ret;
 
 		return *(char*)[obj item: [self items]] * -1;
 	}
 }
+
+- (uint32_t)hash
+{
+	uint32_t hash;
+	size_t i;
+
+	OF_HASH_INIT(hash);
+	for (i = 0; i < items * itemsize; i++)
+		OF_HASH_ADD(hash, ((char*)data)[i]);
+	OF_HASH_FINALIZE(hash);
+
+	return hash;
+}
 @end
 
 @implementation OFBigArray
 - initWithItemSize: (size_t)is
 {

Index: src/OFMacros.h
==================================================================
--- src/OFMacros.h
+++ src/OFMacros.h
@@ -40,5 +40,19 @@
 #define OF_BSWAP_V(buf, len)
 #endif
 
 #define OF_ROL(val, bits) \
 	(((val) << (bits)) | ((val) >> (32 - (bits))))
+
+#define OF_HASH_INIT(hash) hash = 0
+#define OF_HASH_ADD(hash, byte)		\
+	{				\
+		hash += byte;		\
+		hash += (hash << 10);	\
+		hash ^= (hash >> 6);	\
+	}
+#define OF_HASH_FINALIZE(hash)		\
+	{				\
+		hash += (hash << 3);	\
+		hash ^= (hash >> 11);	\
+		hash += (hash << 15);	\
+	}

Index: src/OFObject.m
==================================================================
--- src/OFObject.m
+++ src/OFObject.m
@@ -79,11 +79,11 @@
 }
 
 - (uint32_t)hash
 {
 	/* Classes containing data should reimplement this! */
-	return (uint32_t)self & 0xFFFFFF;
+	return (uint32_t)self;
 }
 
 - addToMemoryPool: (void*)ptr
 {
 	void **memchunks;

Index: src/OFString.m
==================================================================
--- src/OFString.m
+++ src/OFString.m
@@ -285,10 +285,23 @@
 	if (![obj isKindOf: [OFString class]])
 		@throw [OFInvalidArgumentException newWithClass: [self class]];
 
 	return strcmp(string, [obj cString]);
 }
+
+- (uint32_t)hash
+{
+	uint32_t hash;
+	size_t i;
+
+	OF_HASH_INIT(hash);
+	for (i = 0; i < length; i++)
+		OF_HASH_ADD(hash, string[i]);
+	OF_HASH_FINALIZE(hash);
+
+	return hash;
+}
 
 - append: (OFString*)str
 {
 	return [self appendCString: [str cString]];
 }

Index: tests/OFArray/OFArray.m
==================================================================
--- tests/OFArray/OFArray.m
+++ tests/OFArray/OFArray.m
@@ -133,40 +133,50 @@
 
 	if (![x isEqual: y]) {
 		puts("FAIL 1!");
 		return 1;
 	}
+
+	if ([x hash] != [y hash]) {
+		puts("FAIL 2!");
+		return 1;
+	}
 
 	[x add: "x"];
 	if ([x isEqual: y]) {
-		puts("FAIL 2!");
-		return 2;
+		puts("FAIL 3!");
+		return 1;
 	}
 	[pool releaseObjects];
 
 	x = [OFArray arrayWithItemSize: 2];
 	y = [OFArray bigArrayWithItemSize: 4];
 
 	if ([x isEqual: y]) {
-		puts("FAIL 3!");
+		puts("FAIL 4!");
 		return 1;
 	}
 	[pool releaseObjects];
 
 	x = [OFArray arrayWithItemSize: 1];
 	[x addNItems: 3
 	  fromCArray: "abc"];
 	y = [x copy];
 	if ([x compare: y]) {
-		puts("FAIL 4!");
+		puts("FAIL 5!");
 		return 1;
 	}
 
 	[y add: "de"];
 	if ([x compare: y] != -100) {
-		puts("FAIL 5!");
+		puts("FAIL 6!");
+		return 1;
+	}
+
+	if ([y hash] != 0xCD8B6206) {
+		puts("FAIL 7!");
 		return 1;
 	}
 	[pool release];
 
 	return 0;
 }

Index: tests/OFString/OFString.m
==================================================================
--- tests/OFString/OFString.m
+++ tests/OFString/OFString.m
@@ -23,11 +23,11 @@
 #define ZD "%zd"
 #else
 #define ZD "%u"
 #endif
 
-#define NUM_TESTS 13
+#define NUM_TESTS 15
 #define SUCCESS								\
 	printf("\r\033[1;%dmTests successful: " ZD "/%d\033[0m",	\
 	    (i == NUM_TESTS - 1 ? 32 : 33), i + 1, NUM_TESTS);		\
 	fflush(stdout);
 #define FAIL								\
@@ -62,17 +62,19 @@
 	OFString *s4 = [OFString string];
 
 	s3 = [s1 copy];
 
 	CHECK([s1 isEqual: s3])
-	CHECK(![s1 isEqual: [OFObject new]]);
+	CHECK(![s1 isEqual: [OFObject new]])
+	CHECK([s1 hash] == [s3 hash])
 
 	[s2 appendCString: "123"];
 	[s4 setTo: [s2 cString]];
 
 	CHECK(![s2 compare: s4])
 	CHECK(!strcmp([[s1 append: s2] cString], "test123"))
+	CHECK([s1 hash] == 0xC44F49A4)
 	CHECK(strlen([s1 cString]) == [s1 length] && [s1 length] == 7)
 	CHECK(!strcmp([[s1 reverse] cString], "321tset"))
 	CHECK(!strcmp([[s1 upper] cString], "321TSET"))
 	CHECK(!strcmp([[s1 lower] cString], "321tset"))