diff --git a/kernel/signal.cpp b/kernel/signal.cpp
index 6c52febb..e9ec3324 100644
--- a/kernel/signal.cpp
+++ b/kernel/signal.cpp
@@ -617,6 +617,7 @@ retry_another_signal:
 		intctx->cs = UCS | URPL;
 		intctx->ds = UDS | URPL;
 		intctx->ss = UDS | URPL;
+		intctx->ebx = 0;
 #elif defined(__x86_64__)
 		intctx->rip = intctx->rdi;
 		intctx->rflags = intctx->rsi;
@@ -624,6 +625,9 @@ retry_another_signal:
 		intctx->cs = UCS | URPL;
 		intctx->ds = UDS | URPL;
 		intctx->ss = UDS | URPL;
+		intctx->rdi = 0;
+		intctx->rsi = 0;
+		intctx->r8 = 0;
 #else
 #error "You may need to fix the registers"
 #endif
diff --git a/kernel/x64/syscall.S b/kernel/x64/syscall.S
index 651d221e..958471f2 100644
--- a/kernel/x64/syscall.S
+++ b/kernel/x64/syscall.S
@@ -1,6 +1,6 @@
 /*******************************************************************************
 
-    Copyright(C) Jonas 'Sortie' Termansen 2011, 2012, 2013, 2014.
+    Copyright(C) Jonas 'Sortie' Termansen 2011, 2012, 2013, 2014, 2015.
 
     This file is part of Sortix.
 
@@ -36,9 +36,9 @@ syscall_handler:
 
 	# Make sure the requested system call is valid, if not, then fix it.
 	cmp $SYSCALL_MAX_NUM, %rax
-	jae fix_syscall
+	jae 3f
 
-valid_syscall:
+1:
 	# Read a system call function pointer.
 	xorq %r11, %r11
 	movq syscall_list(%r11,%rax,8), %rax
@@ -52,19 +52,33 @@ valid_syscall:
 	popq %rbp
 	movl global_errno, %ecx
 
+	# Zero registers to avoid information leaks.
+	# rax is return value.
+	# rdi is set in a moment.
+	xor %rsi, %rsi
+	# rdx is return value (MIGHT NOT BE INITIALIZED, CAN LEAK!).
+	# rcx is errno.
+	xor %r8, %r8
+	xor %r9, %r9
+	xor %r10, %r10
+	xor %r11, %r11
+	# The rest of the registers are preserved by the ABI and syscall ABI.
+
 	# If any signals are pending, fire them now.
 	movq asm_signal_is_pending, %rdi
 	testq %rdi, %rdi
-	jnz call_signal_dispatcher
+	jnz 4f
+	# rdi is zero in this branch.
 
+2:
 	iretq
 
-fix_syscall:
+3:
 	# Call the null system call instead.
 	xorq %rax, %rax
-	jmp valid_syscall
+	jmp 1b
 
-call_signal_dispatcher:
+4:
 	# We can't return to this location after the signal, since if any system
 	# call is made this stack will get reused and all our nice temporaries wil
 	# be garbage. We therefore pass the kernel the state to return to and it'll
@@ -74,7 +88,11 @@ call_signal_dispatcher:
 	movq 24(%rsp), %r8 # userspace rsp, note %rcx is used for errno
 	int $130 # Deliver pending signals.
 	# If we end up here, it means that the signal didn't override anything and
-	# that we should just go ahead and return to userspace ourselves.
-	iretq
+	# that we should just go ahead and return to userspace ourselves. Zero the
+	# scratch registers to avoid information leaks.
+	xor %rdi, %rdi
+	xor %rsi, %rsi
+	xor %r8, %r8
+	jmp 2b
 
 .size syscall_handler, .-syscall_handler
diff --git a/kernel/x86/syscall.S b/kernel/x86/syscall.S
index 85ec29b3..89d634b2 100644
--- a/kernel/x86/syscall.S
+++ b/kernel/x86/syscall.S
@@ -1,6 +1,6 @@
 /*******************************************************************************
 
-    Copyright(C) Jonas 'Sortie' Termansen 2011, 2012, 2013, 2014.
+    Copyright(C) Jonas 'Sortie' Termansen 2011, 2012, 2013, 2014, 2015.
 
     This file is part of Sortix.
 
@@ -45,9 +45,9 @@ syscall_handler:
 
 	# Make sure the requested system call is valid.
 	cmp $SYSCALL_MAX_NUM, %eax
-	jae fix_syscall
+	jae 3f
 
-valid_syscall:
+1:
 	# Read a system call function pointer.
 	xorl %ebp, %ebp
 	movl syscall_list(%ebp,%eax,4), %eax
@@ -76,19 +76,28 @@ valid_syscall:
 	popl %ebp
 	movl global_errno, %ecx
 
+	# Zero registers to avoid information leaks.
+	# eax is the return value.
+	# ecx is errno.
+	# edx is the return value (MIGHT NOT BE INITIALIZED, CAN LEAK!).
+	# ebx is set in a moment.
+	xor %esi, %esi
+	xor %edi, %edi
 	# If any signals are pending, fire them now.
 	movl asm_signal_is_pending, %ebx
 	testl %ebx, %ebx
-	jnz call_signal_dispatcher
+	jnz 4f
+	# ebx is zero in this branch.
 
+2:
 	iretl
 
-fix_syscall:
+3:
 	# Call the null system call instead.
 	xorl %eax, %eax
-	jmp valid_syscall
+	jmp 1b
 
-call_signal_dispatcher:
+4:
 	# We can't return to this location after the signal, since if any system
 	# call is made this stack will get reused and all our nice temporaries wil
 	# be garbage. We therefore pass the kernel the state to return to and it'll
@@ -97,6 +106,7 @@ call_signal_dispatcher:
 	int $130 # Deliver pending signals.
 	# If we end up here, it means that the signal didn't override anything and
 	# that we should just go ahead and return to userspace ourselves.
-	iretl
+	xor %ebx, %ebx
+	jmp 2b
 
 .size syscall_handler, .-syscall_handler