diff --git a/ChangeLog b/ChangeLog
index 2c82e1025..5c204ee90 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,18 @@
+2013-12-30  Marcus Mueller <znek@mulle-kybernetik.com>
+
+	* Headers/GNUstepBase/GSVersionMacros.h: added macros
+	GS_GCC_MINREQ(maj,min) and GS_CLANG_MINREQ(maj,min) to check for
+	minimum required versions of GCC and CLANG compilers. Changed several
+	occurrences of previous macros to improve readability.
+	Added GS_PROTOCOLS_HAVE_OPTIONAL to correctly mark all appropriate
+	declarations.
+	* Headers/Foundation/NSNetServices.h,
+	* Headers/Foundation/NSStream.h,
+	* Headers/Foundation/NSXMLParser.h,
+	* Headers/GNUstepBase/NSNetServices+GNUstepBase.h,
+	* Source/GSNetServices.h:
+	use GS_PROTOCOLS_HAVE_OPTIONAL macro where appropriate
+
 2013-12-26  Marcus Mueller <znek@mulle-kybernetik.com>
 
 	* Headers/Foundation/NSNetServices.h:
diff --git a/Headers/Foundation/NSNetServices.h b/Headers/Foundation/NSNetServices.h
index 46934c05d..33612d3f4 100644
--- a/Headers/Foundation/NSNetServices.h
+++ b/Headers/Foundation/NSNetServices.h
@@ -114,7 +114,7 @@ GS_EXPORT NSString * const NSNetServicesErrorDomain;
 
 
 @protocol  NSNetServiceDelegate
-#ifdef __clang__ /* FIXME ... this is not clang specific */
+#if OS_API_VERSION(MAC_OS_X_VERSION_10_6,GS_API_LATEST) && GS_PROTOCOLS_HAVE_OPTIONAL
 @optional
 #else
 @end
@@ -243,7 +243,7 @@ GS_EXPORT NSString * const NSNetServicesErrorDomain;
  */
 
 @protocol NSNetServiceBrowserDelegate
-#ifdef __clang__ /* FIXME ... this is not clang specific */
+#if OS_API_VERSION(MAC_OS_X_VERSION_10_6,GS_API_LATEST) && GS_PROTOCOLS_HAVE_OPTIONAL
 @optional
 #else
 @end
diff --git a/Headers/Foundation/NSStream.h b/Headers/Foundation/NSStream.h
index 5af2fa27a..292e1c598 100644
--- a/Headers/Foundation/NSStream.h
+++ b/Headers/Foundation/NSStream.h
@@ -270,8 +270,7 @@ GS_EXPORT NSString * const NSStreamSOCKSProxyVersion4;
 GS_EXPORT NSString * const NSStreamSOCKSProxyVersion5;
 GS_EXPORT NSString * const NSStreamSOCKSProxyVersionKey;
 
-#if OS_API_VERSION(MAC_OS_X_VERSION_10_7,GS_API_LATEST) && defined(__clang__)
-/* FIXME ... this is not clang specific */ 
+#if OS_API_VERSION(MAC_OS_X_VERSION_10_7,GS_API_LATEST) && GS_PROTOCOLS_HAVE_OPTIONAL
 @protocol NSStreamDelegate <NSObject> 
 @optional 
 #else 
diff --git a/Headers/Foundation/NSXMLParser.h b/Headers/Foundation/NSXMLParser.h
index df862a75d..c8e01d51b 100644
--- a/Headers/Foundation/NSXMLParser.h
+++ b/Headers/Foundation/NSXMLParser.h
@@ -190,7 +190,7 @@ GS_EXPORT NSString* const NSXMLParserErrorDomain;
  * This is now a formal protocol.
  */
 @protocol NSXMLParserDelegate <NSObject>
-#ifdef __clang__ /* FIXME ... this is not clang specific */
+#if OS_API_VERSION(MAC_OS_X_VERSION_10_6,GS_API_LATEST) && GS_PROTOCOLS_HAVE_OPTIONAL
 @optional
 #else
 @end
diff --git a/Headers/GNUstepBase/GSVersionMacros.h b/Headers/GNUstepBase/GSVersionMacros.h
index 27cc99d4e..374d015b8 100644
--- a/Headers/GNUstepBase/GSVersionMacros.h
+++ b/Headers/GNUstepBase/GSVersionMacros.h
@@ -220,6 +220,20 @@
 #endif
 
 
+#if defined(__GNUC__) && defined(__GNUC_MINOR__) && !defined(__clang__)
+#  define GS_GCC_MINREQ(maj, min) \
+  ((__GNUC__ << 16) + __GNUC_MINOR__ >= ((maj) << 16) + (min))
+#else
+#  define GS_GCC_MINREQ(maj, min) 0
+#endif
+
+#if defined(__clang__)
+#  define GS_CLANG_MINREQ(maj, min) \
+  ((__clang_major__ << 16) + __clang_minor__ >= ((maj) << 16) + (min))
+#else
+#  define GS_CLANG_MINREQ(maj, min) 0
+#endif
+
 /* Attribute definitions for attributes which may or may not be supported
  * depending on the compiler being used.
  * NB we currently expect gcc to be version 4 or later.
@@ -229,7 +243,7 @@
  * depending on where the attribute can be applied.
  */
 
-#if __GNUC__*10+__GNUC_MINOR__ >= 31
+#if defined(__clang__) || GS_GCC_MINREQ(3,1)
 #  define GS_DEPRECATED_FUNC __attribute__ ((deprecated))
 #else
 #  define GS_DEPRECATED_FUNC
@@ -392,7 +406,7 @@ static inline void gs_consumed(id NS_CONSUMED GS_UNUSED_ARG o) { return; }
 /* Attribute macros compatible with Apple.
  */
 
-#if __GNUC__*10+__GNUC_MINOR__ >= 42
+#if defined(__clang__) || GS_GCC_MINREQ(4,2)
 #  define NS_FORMAT_ARGUMENT(A) __attribute__((format_arg(A)))
 #else
 #  define NS_FORMAT_ARGUMENT(F,A) 
@@ -407,5 +421,12 @@ static inline void gs_consumed(id NS_CONSUMED GS_UNUSED_ARG o) { return; }
 
 #define NS_REQUIRES_NIL_TERMINATION __attribute__((sentinel))
 
+/* Check if compiler supports @optional in protocols
+ */
+#if defined(__clang__) || GS_GCC_MINREQ(4,6)
+#  define GS_PROTOCOLS_HAVE_OPTIONAL 1
+#else
+#  define GS_PROTOCOLS_HAVE_OPTIONAL 0
+#endif
 
 #endif /* __GNUSTEP_GSVERSIONMACROS_H_INCLUDED_ */
diff --git a/Headers/GNUstepBase/NSNetServices+GNUstepBase.h b/Headers/GNUstepBase/NSNetServices+GNUstepBase.h
index 2f1820386..2a642d95c 100644
--- a/Headers/GNUstepBase/NSNetServices+GNUstepBase.h
+++ b/Headers/GNUstepBase/NSNetServices+GNUstepBase.h
@@ -81,12 +81,12 @@
 
 
 @protocol  GSNetServiceDelegate <NSNetServiceDelegate>
-#ifdef __clang__
+#if GS_PROTOCOLS_HAVE_OPTIONAL
 @optional
 #else
 @end
 @interface NSObject (GSNetServiceDelegateMethods)
-#endif // __clang__
+#endif // GS_PROTOCOLS_HAVE_OPTIONAL
 
 /**
  * Notifies the delegate that the addresses for the <var>service</var> have
diff --git a/Source/GSNetServices.h b/Source/GSNetServices.h
index cdf748fb7..93a78c0df 100644
--- a/Source/GSNetServices.h
+++ b/Source/GSNetServices.h
@@ -74,11 +74,7 @@ NSString* GSNetServiceDotTerminatedNSStringFromString(const char* string);
 /**
  * NSNetService using the avahi-client API.
  */
-#ifdef __clang__        /* FIXME ... this is not clang specific! */
 @interface GSAvahiNetService : NSNetService <NSNetServiceDelegate>
-#else
-@interface GSAvahiNetService : NSNetService
-#endif
 {
   // GSAvahiClient behaviour ivars:
   // From superclass: id _delegate;
@@ -120,12 +116,8 @@ NSString* GSNetServiceDotTerminatedNSStringFromString(const char* string);
 /**
  * NSNetServiceBrowser using the avahi-client API.
  */
-#ifdef __clang__        /* FIXME ... this is not clang specific! */
 @interface GSAvahiNetServiceBrowser
   : NSNetServiceBrowser <NSNetServiceBrowserDelegate>
-#else
-@interface GSAvahiNetServiceBrowser: NSNetServiceBrowser
-#endif
 {
   // GSAvahiClient behaviour ivars:
   // from superclass: id _delegate;
@@ -147,21 +139,13 @@ NSString* GSNetServiceDotTerminatedNSStringFromString(const char* string);
 /**
  * NSNetService using the mDNSResponder API.
  */
-#ifdef __clang__        /* FIXME ... this is not clang specific! */
 @interface GSMDNSNetService : NSNetService <NSNetServiceDelegate>
-#else
-@interface GSMDNSNetService : NSNetService
-#endif
 @end
 
 /**
  * NSNetServiceBrowser using the mDNSResponder API.
  */
-#ifdef __clang__        /* FIXME ... this is not clang specific! */
 @interface GSMDNSNetServiceBrowser : NSNetServiceBrowser <NSNetServiceBrowserDelegate>
-#else
-@interface GSMDNSNetServiceBrowser : NSNetServiceBrowser
-#endif
 @end
 
 #endif // GS_USE_AVAHI