diff --git a/src/system/kernel/arch/x86/arch_int.c b/src/system/kernel/arch/x86/arch_int.c
index 9d1a57051b..c612ec6960 100644
--- a/src/system/kernel/arch/x86/arch_int.c
+++ b/src/system/kernel/arch/x86/arch_int.c
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2006, Axel Dörfler, axeld@pinc-software.de.
+ * Copyright 2002-2008, Axel Dörfler, axeld@pinc-software.de.
  * Distributed under the terms of the MIT License.
  *
  * Copyright 2001, Travis Geiselbrecht. All rights reserved.
@@ -225,6 +225,12 @@ pic_init(void)
 
 	// determine which interrupts are level or edge triggered
 
+#if 0
+	// should set everything possible to level triggered
+	out8(PIC_MASTER_TRIGGER_MODE, 0xf8);
+	out8(PIC_SLAVE_TRIGGER_MODE, 0xde);
+#endif
+
 	sLevelTriggeredInterrupts = in8(PIC_MASTER_TRIGGER_MODE)
 		| (in8(PIC_SLAVE_TRIGGER_MODE) << 8);
 
@@ -453,7 +459,7 @@ page_fault_exception(struct iframe* frame)
 
 	if (kernelDebugger) {
 		// if this thread has a fault handler, we're allowed to be here
-		if (thread && thread->fault_handler != NULL) {
+		if (thread && thread->fault_handler != 0) {
 			frame->eip = thread->fault_handler;
 			return;
 		}
diff --git a/src/system/kernel/arch/x86/arch_thread.cpp b/src/system/kernel/arch/x86/arch_thread.cpp
index aa4f4abaae..3b4f5c003f 100644
--- a/src/system/kernel/arch/x86/arch_thread.cpp
+++ b/src/system/kernel/arch/x86/arch_thread.cpp
@@ -353,7 +353,7 @@ arch_thread_context_switch(struct thread *from, struct thread *to)
 
 	// set TLS GDT entry to the current thread - since this action is
 	// dependent on the current CPU, we have to do it here
-	if (to->user_local_storage != NULL)
+	if (to->user_local_storage != 0)
 		set_tls_context(to);
 
 	newPageDirectory = (addr_t)x86_next_page_directory(from, to);
diff --git a/src/system/kernel/debug/frame_buffer_console.cpp b/src/system/kernel/debug/frame_buffer_console.cpp
index 527d0c4e7b..957d4f2f4c 100644
--- a/src/system/kernel/debug/frame_buffer_console.cpp
+++ b/src/system/kernel/debug/frame_buffer_console.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright 2005-2007, Axel Dörfler, axeld@pinc-software.de. All rights reserved.
+ * Copyright 2005-2008, Axel Dörfler, axeld@pinc-software.de. All rights reserved.
  * Distributed under the terms of the MIT License.
  */
 
@@ -381,7 +381,7 @@ frame_buffer_update(addr_t baseAddress, int32 width, int32 height, int32 depth,
 bool
 frame_buffer_console_available(void)
 {
-	return sConsole.frame_buffer != NULL;
+	return sConsole.frame_buffer != 0;
 }
 
 
@@ -425,8 +425,7 @@ frame_buffer_console_init_post_modules(kernel_args *args)
 {
 	mutex_init(&sConsole.lock, "console_lock");
 
-	// TODO: enable MTRR in VESA mode!
-	if (sConsole.frame_buffer == NULL)
+	if (sConsole.frame_buffer == 0)
 		return B_OK;
 
 	// try to set frame buffer memory to write combined
@@ -447,7 +446,7 @@ _user_frame_buffer_update(addr_t baseAddress, int32 width, int32 height,
 
 	if (geteuid() != 0)
 		return B_NOT_ALLOWED;
-	if (IS_USER_ADDRESS(baseAddress) && baseAddress != NULL)
+	if (IS_USER_ADDRESS(baseAddress) && baseAddress != 0)
 		return B_BAD_ADDRESS;
 
 	return frame_buffer_update(baseAddress, width, height, depth, bytesPerRow);
diff --git a/src/system/kernel/module.cpp b/src/system/kernel/module.cpp
index eb9f3ff8fc..3cba5ed399 100644
--- a/src/system/kernel/module.cpp
+++ b/src/system/kernel/module.cpp
@@ -1262,7 +1262,7 @@ get_next_loaded_module_name(uint32 *_cookie, char *buffer, size_t *_bufferSize)
 {
 	if (sModulesHash == NULL) {
 		dprintf("get_next_loaded_module_name() called too early!\n");
-		return NULL;
+		return B_ERROR;
 	}
 
 	//TRACE(("get_next_loaded_module_name(\"%s\")\n", buffer));
diff --git a/src/system/kernel/signal.cpp b/src/system/kernel/signal.cpp
index ff0582f73c..6aa3ab28f6 100644
--- a/src/system/kernel/signal.cpp
+++ b/src/system/kernel/signal.cpp
@@ -724,7 +724,7 @@ sigaction_etc(thread_id threadID, int signal, const struct sigaction *act,
 			// remove pending signal if it should now be ignored
 			atomic_and(&thread->sig_pending, ~SIGNAL_TO_MASK(signal));
 		} else if (act && act->sa_handler == SIG_DFL
-			&& (SIGNAL_TO_MASK(signal) & DEFAULT_IGNORE_SIGNALS) != NULL) {
+			&& (SIGNAL_TO_MASK(signal) & DEFAULT_IGNORE_SIGNALS) != 0) {
 			// remove pending signal for those signals whose default
 			// action is to ignore them
 			atomic_and(&thread->sig_pending, ~SIGNAL_TO_MASK(signal));
diff --git a/src/system/kernel/vm/vm.cpp b/src/system/kernel/vm/vm.cpp
index a105ef0343..68b4fd55f5 100644
--- a/src/system/kernel/vm/vm.cpp
+++ b/src/system/kernel/vm/vm.cpp
@@ -1434,7 +1434,7 @@ vm_create_anonymous_area(team_id team, const char *name, void **address,
 
 	AddressSpaceWriteLocker locker;
 	status_t status = locker.SetTo(team);
-	if (status != NULL)
+	if (status != B_OK)
 		return status;
 
 	vm_address_space *addressSpace = locker.AddressSpace();
@@ -2837,7 +2837,7 @@ dump_cache_tree(int argc, char **argv)
 	}
 
 	addr_t address = strtoul(argv[1], NULL, 0);
-	if (address == NULL)
+	if (address == 0)
 		return 0;
 
 	vm_cache *cache = (vm_cache *)address;
@@ -2923,7 +2923,7 @@ dump_cache(int argc, char **argv)
 	}
 
 	addr_t address = strtoul(argv[i], NULL, 0);
-	if (address == NULL)
+	if (address == 0)
 		return 0;
 
 	cache = (vm_cache *)address;