diff --git a/reactos/ReactOS-generic.rbuild b/reactos/ReactOS-generic.rbuild
index 6bff3736313..215e42b8016 100644
--- a/reactos/ReactOS-generic.rbuild
+++ b/reactos/ReactOS-generic.rbuild
@@ -3,7 +3,7 @@
 <group xmlns:xi="http://www.w3.org/2001/XInclude">
 	<xi:include href="baseaddress.rbuild" />
 
-	<define name="_REACTOS_" />
+	<define name="__REACTOS__" />
 	<if property="MP" value="1">
 		<define name="CONFIG_SMP" value="1" />
 	</if>
diff --git a/reactos/ReactOS-ppc.rbuild b/reactos/ReactOS-ppc.rbuild
index a0882d399f5..1abfd145974 100644
--- a/reactos/ReactOS-ppc.rbuild
+++ b/reactos/ReactOS-ppc.rbuild
@@ -10,30 +10,29 @@
 	<xi:include href="ReactOS-generic.rbuild" />
 
 	<property name="OFWLDR_LINKFORMAT" value="-L$(INTERMEDIATE)/lib/ppcmmu -lppcmmu_code -nostdlib -nostartfiles -lgcc -Wl,-e,__start -Wl,-Ttext,0xe00000 -N"/>
-        <property name="NTOSKRNL_SHARED" value="-Wl,--file-alignment,0x1000 -Wl,--section-alignment,0x1000 -nostartfiles"/>
+	<property name="NTOSKRNL_SHARED" value="-Wl,--file-alignment,0x1000 -Wl,--section-alignment,0x1000 -nostartfiles"/>
 
-  <define name="_M_PPC" />
-  <define name="_PPC_" />
-  <define name="__PowerPC__" />
-  <define name="_REACTOS_" />
-  <define name="stdcall" empty="true" />	
-  <define name="__stdcall__" empty="true" />
-  <define name="fastcall" empty="true" />
-  <define name="cdecl" empty="true" />
-  <define name="__cdecl__" empty="true" />
-  <define name="dllimport" empty="true" />
-  <define name="WORDS_BIGENDIAN" empty="true" />
-  <define name="__MSVCRT__" empty="true" />
-  <define name="__NO_CTYPE_INLINES" />
-  <define name="__DECLSPEC_SUPPORTED" />
-  <define name="__MINGW_IMPORT">extern</define>
-  <define name="_CRTIMP" empty="true" />
-  <define name="'__declspec(x)'" empty="true" />
-  <compilerflag>-fshort-wchar</compilerflag>
-  <compilerflag>-fsigned-char</compilerflag>
-  <compilerflag>-mfull-toc</compilerflag>
-  <compilerflag>-meabi</compilerflag>
-  <compilerflag>-O2</compilerflag>
-  <compilerflag>-Wno-strict-aliasing</compilerflag>
+	<define name="_M_PPC" />
+	<define name="_PPC_" />
+	<define name="__PowerPC__" />
+	<define name="stdcall" empty="true" />
+	<define name="__stdcall__" empty="true" />
+	<define name="fastcall" empty="true" />
+	<define name="cdecl" empty="true" />
+	<define name="__cdecl__" empty="true" />
+	<define name="dllimport" empty="true" />
+	<define name="WORDS_BIGENDIAN" empty="true" />
+	<define name="__MSVCRT__" empty="true" />
+	<define name="__NO_CTYPE_INLINES" />
+	<define name="__DECLSPEC_SUPPORTED" />
+	<define name="__MINGW_IMPORT">extern</define>
+	<define name="_CRTIMP" empty="true" />
+	<define name="'__declspec(x)'" empty="true" />
+	<compilerflag>-fshort-wchar</compilerflag>
+	<compilerflag>-fsigned-char</compilerflag>
+	<compilerflag>-mfull-toc</compilerflag>
+	<compilerflag>-meabi</compilerflag>
+	<compilerflag>-O2</compilerflag>
+	<compilerflag>-Wno-strict-aliasing</compilerflag>
 
 </project>
diff --git a/reactos/base/services/dhcp/dhclient.c b/reactos/base/services/dhcp/dhclient.c
index 4cfa0210182..dedc622fe2a 100644
--- a/reactos/base/services/dhcp/dhclient.c
+++ b/reactos/base/services/dhcp/dhclient.c
@@ -433,7 +433,7 @@ dhcpack(struct packet *packet)
 		ip->client->new->rebind = ip->client->new->renewal +
 		    ip->client->new->renewal / 2 + ip->client->new->renewal / 4;
 
-#ifdef _REACTOS_
+#ifdef __REACTOS__
 	ip->client->new->obtained = cur_time;
 #endif
 	ip->client->new->expiry += cur_time;
@@ -825,7 +825,7 @@ packet_to_lease(struct packet *packet)
 
 	lease->address.len = sizeof(packet->raw->yiaddr);
 	memcpy(lease->address.iabuf, &packet->raw->yiaddr, lease->address.len);
-#ifdef _REACTOS_
+#ifdef __REACTOS__
 	lease->serveraddress.len = sizeof(packet->raw->siaddr);
 	memcpy(lease->serveraddress.iabuf, &packet->raw->siaddr, lease->address.len);
 #endif
diff --git a/reactos/base/services/dhcp/include/dhcpd.h b/reactos/base/services/dhcp/include/dhcpd.h
index 3e9dd53d90c..48b91d57787 100644
--- a/reactos/base/services/dhcp/include/dhcpd.h
+++ b/reactos/base/services/dhcp/include/dhcpd.h
@@ -158,7 +158,7 @@ struct client_lease {
 	time_t			 expiry, renewal, rebind;
 	struct iaddr		 address;
 	char			*server_name;
-#ifdef _REACTOS_
+#ifdef __REACTOS__
 	time_t			 obtained;
 	struct iaddr		 serveraddress;
 #endif
@@ -178,7 +178,7 @@ enum dhcp_state {
 	S_BOUND,
 	S_RENEWING,
 	S_REBINDING,
-        S_STATIC
+	S_STATIC
 };
 
 struct client_config {
diff --git a/reactos/include/ndk/i386/ketypes.h b/reactos/include/ndk/i386/ketypes.h
index ebb5a01877d..1abaa1f89f0 100644
--- a/reactos/include/ndk/i386/ketypes.h
+++ b/reactos/include/ndk/i386/ketypes.h
@@ -628,7 +628,7 @@ typedef struct _KIPCR
     ULONG IDR;
     PVOID KdVersionBlock;
     PKIDTENTRY IDT;
-#ifdef _REACTOS_
+#ifdef __REACTOS__
     PUSHORT GDT;
 #else
     PKGDTENTRY GDT;
diff --git a/reactos/include/psdk/rpc.h b/reactos/include/psdk/rpc.h
index ca4f8a45092..1b1c00d0d7e 100644
--- a/reactos/include/psdk/rpc.h
+++ b/reactos/include/psdk/rpc.h
@@ -22,7 +22,7 @@
 extern "C" {
 #endif
 
-#if defined( MAC ) || defined( _MAC ) || defined(__powerpc__) && !defined(_REACTOS_)
+#if defined( MAC ) || defined( _MAC ) || defined(__powerpc__) && !defined(__REACTOS__)
     #define __RPC_MAC__
     #define __RPC_WIN32__
     #include <pshpack2.h>