diff --git a/sortix/scheduler.cpp b/sortix/scheduler.cpp
index 51a69594..c050a3d4 100644
--- a/sortix/scheduler.cpp
+++ b/sortix/scheduler.cpp
@@ -143,6 +143,15 @@ namespace Sortix
 			nextthread->LoadRegisters(regs);
 
 			addr_t newaddrspace = nextthread->process->addrspace;
+			if ( unlikely(newaddrspace != Page::AlignDown(newaddrspace)) )
+			{
+				PanicF("Thread 0x%p, process %i (0x%p) (backup: %i), had bad "
+				       "address space variable: 0x%zx: not page-aligned "
+				       "(backup: 0x%zx)\n", nextthread,
+				       nextthread->process->pid, nextthread->process,
+				       nextthread->pidbackup, newaddrspace,
+				       nextthread->addrspacebackup);
+			}
 			Memory::SwitchAddressSpace(newaddrspace);
 			currentthread = nextthread;
 
diff --git a/sortix/thread.cpp b/sortix/thread.cpp
index b1bb7128..579acbac 100644
--- a/sortix/thread.cpp
+++ b/sortix/thread.cpp
@@ -56,6 +56,7 @@ namespace Sortix
 		currentsignal = NULL;
 		sighandler = NULL;
 		pidbackup = -1;
+		addrspacebackup = 0UL;
 		terminated = false;
 		ResetCallbacks();
 	}
@@ -80,6 +81,7 @@ namespace Sortix
 		scfunc = NULL;
 		sighandler = forkfrom->sighandler;
 		pidbackup = -1;
+		addrspacebackup = 0UL;
 		terminated = false;
 		ResetCallbacks();
 	}
@@ -190,6 +192,7 @@ namespace Sortix
 		ready = true;
 
 		this->pidbackup = process->pid;
+		this->addrspacebackup = process->addrspace;
 
 		if ( Time::MicrosecondsSinceBoot() < sleepuntil )
 		{
diff --git a/sortix/thread.h b/sortix/thread.h
index 47e8bc8a..5ff62eb3 100644
--- a/sortix/thread.h
+++ b/sortix/thread.h
@@ -61,6 +61,7 @@ namespace Sortix
 		size_t id;
 		Process* process;
 		pid_t pidbackup;
+		addr_t addrspacebackup;
 		bool terminated;
 		Thread* prevsibling;
 		Thread* nextsibling;
diff --git a/sortix/x86-family/memorymanagement.cpp b/sortix/x86-family/memorymanagement.cpp
index 5fed13a1..8a37ff36 100644
--- a/sortix/x86-family/memorymanagement.cpp
+++ b/sortix/x86-family/memorymanagement.cpp
@@ -265,11 +265,14 @@ namespace Sortix
 		addr_t Get()
 		{
 			if ( unlikely(stackused == 0) ) { Error::Set(ENOMEM); return 0; }
-			return STACK[--stackused];
+			addr_t result = STACK[--stackused];
+			ASSERT(result == AlignDown(result));
+			return result;
 		}
 
 		void Put(addr_t page)
 		{
+			ASSERT(page == AlignDown(page));
 			ASSERT(stackused < MAXSTACKLENGTH);
 			STACK[stackused++] = page;
 		}