Index: src/OFDate.h
==================================================================
--- src/OFDate.h
+++ src/OFDate.h
@@ -24,19 +24,12 @@
 /**
  * @class OFDate OFDate.h ObjFW/OFDate.h
  *
  * @brief A class for storing, accessing and comparing dates.
  */
-#ifndef OF_DATE_M
-OF_SUBCLASSING_RESTRICTED
-#endif
 @interface OFDate: OFObject <OFCopying, OFComparing,
     OFMessagePackRepresentation>
-{
-	OFTimeInterval _seconds;
-}
-
 #ifdef OF_HAVE_CLASS_PROPERTIES
 @property (class, readonly, nonatomic) OFDate *distantFuture;
 @property (class, readonly, nonatomic) OFDate *distantPast;
 #endif
 

Index: src/OFDate.m
==================================================================
--- src/OFDate.m
+++ src/OFDate.m
@@ -44,18 +44,20 @@
 #if defined(OF_AMIGAOS_M68K) || defined(OF_MINT)
 /* amiga-gcc and freemint-gcc do not have trunc() */
 # define trunc(x) ((int64_t)(x))
 #endif
 
-@interface OFDate ()
-+ (instancetype)of_alloc;
+@interface OFDatePlaceholder: OFDate
 @end
 
-@interface OFDateSingleton: OFDate
+@interface OFConcreteDate: OFDate
+{
+	OFTimeInterval _seconds;
+}
 @end
 
-@interface OFDatePlaceholder: OFDateSingleton
+@interface OFDateSingleton: OFConcreteDate
 @end
 
 #if defined(OF_OBJFW_RUNTIME) && UINTPTR_MAX == UINT64_MAX
 @interface OFTaggedPointerDate: OFDateSingleton
 @end
@@ -311,16 +313,33 @@
 		if (ret != nil)
 			return ret;
 	}
 #endif
 
-	return (id)[[OFDate of_alloc] initWithTimeIntervalSince1970: seconds];
+	return (id)[[OFConcreteDate alloc]
+	    initWithTimeIntervalSince1970: seconds];
 }
 #ifdef __clang__
 # pragma clang diagnostic pop
 #endif
 @end
+
+@implementation OFConcreteDate
+- (instancetype)initWithTimeIntervalSince1970: (OFTimeInterval)seconds
+{
+	self = [super initWithTimeIntervalSince1970: seconds];
+
+	_seconds = seconds;
+
+	return self;
+}
+
+- (OFTimeInterval)timeIntervalSince1970
+{
+	return _seconds;
+}
+@end
 
 #if defined(OF_OBJFW_RUNTIME) && UINTPTR_MAX == UINT64_MAX
 @implementation OFTaggedPointerDate
 - (OFTimeInterval)timeIntervalSince1970
 {
@@ -361,15 +380,10 @@
 #if defined(OF_OBJFW_RUNTIME) && UINTPTR_MAX == UINT64_MAX
 	dateTag = objc_registerTaggedPointerClass([OFTaggedPointerDate class]);
 #endif
 }
 
-+ (instancetype)of_alloc
-{
-	return [super alloc];
-}
-
 + (instancetype)alloc
 {
 	if (self == [OFDate class])
 		return (id)&placeholder;
 
@@ -426,15 +440,22 @@
 	return [self initWithTimeIntervalSince1970: now()];
 }
 
 - (instancetype)initWithTimeIntervalSince1970: (OFTimeInterval)seconds
 {
-	self = [super init];
+	if ([self isMemberOfClass: [OFDate class]]) {
+		@try {
+			[self doesNotRecognizeSelector: _cmd];
+		} @catch (id e) {
+			[self release];
+			@throw e;
+		}
 
-	_seconds = seconds;
+		abort();
+	}
 
-	return self;
+	return [super init];
 }
 
 - (instancetype)initWithTimeIntervalSinceNow: (OFTimeInterval)seconds
 {
 	return [self initWithTimeIntervalSince1970: now() + seconds];
@@ -831,11 +852,11 @@
 	return self;
 }
 
 - (OFTimeInterval)timeIntervalSince1970
 {
-	return _seconds;
+	OF_UNRECOGNIZED_SELECTOR
 }
 
 - (OFTimeInterval)timeIntervalSinceDate: (OFDate *)otherDate
 {
 	return self.timeIntervalSince1970 - otherDate.timeIntervalSince1970;