diff --git a/kernel/src/thread/ThreadImage.cpp b/kernel/src/thread/ThreadImage.cpp
index d937223b..a16ab223 100644
--- a/kernel/src/thread/ThreadImage.cpp
+++ b/kernel/src/thread/ThreadImage.cpp
@@ -1,6 +1,7 @@
 #include "thread/ThreadImage.h"
 #include "memory/MemoryManager.h"
 #include "thread/Thread.h"
+#include <luna/Alignment.h>
 #include <luna/CString.h>
 
 static constexpr usize DEFAULT_USER_STACK_PAGES = 6;
@@ -122,7 +123,7 @@ void ThreadImage::apply(Thread* thread)
 
     thread->kernel_stack = m_kernel_stack;
     thread->stack = m_user_stack;
-    thread->set_sp(m_sp);
+    thread->set_sp(align_down<16>(m_sp));
 
     thread->directory = m_directory;
 
diff --git a/libluna/src/Stack.cpp b/libluna/src/Stack.cpp
index a4fb02ef..7f971403 100644
--- a/libluna/src/Stack.cpp
+++ b/libluna/src/Stack.cpp
@@ -6,5 +6,5 @@ Stack::Stack(u64 base, usize bytes) : m_base(base), m_bytes(bytes)
 
 u64 Stack::top() const
 {
-    return (m_base + m_bytes) - sizeof(void*);
+    return (m_base + m_bytes) - 16;
 }