diff --git a/src/kernel/cpu.cpp b/src/kernel/cpu.cpp
index 71fc366..7033b65 100644
--- a/src/kernel/cpu.cpp
+++ b/src/kernel/cpu.cpp
@@ -118,6 +118,19 @@ cpu_early_init(cpu_data *cpu)
         .set(xcr0::SSE);
     set_xcr0(xcr0_val);
 
+    // Set initial floating point state
+    const util::bitset32 mxcsr_val {
+        mxcsr::DAZ,
+        mxcsr::IM,
+        mxcsr::DM,
+        mxcsr::ZM,
+        mxcsr::OM,
+        mxcsr::UM,
+        mxcsr::PM,
+        mxcsr::FTZ,
+    };
+    asm ( "ldmxcsr %0" :: "m"(mxcsr_val) );
+
     // Install the GS base pointint to the cpu_data
     wrmsr(msr::ia32_gs_base, reinterpret_cast<uintptr_t>(cpu));
 }
@@ -234,3 +247,13 @@ cpu_init(cpu_data *cpu, bool bsp)
 
     xsave_enable();
 }
+
+/// Set up initial per-thread CPU state. Called once from initialize_user_cpu in
+/// syscall.s, the first code run after a thread comes out of task_switch for the
+/// very first time.
+extern "C" void
+cpu_initialize_thread_state()
+{
+    const util::bitset32 &mxcsr_val = obj::thread::current().m_mxcsr;
+    asm ( "ldmxcsr %0" :: "m"(mxcsr_val) );
+}
diff --git a/src/kernel/cpu.h b/src/kernel/cpu.h
index 8912bb1..8168d84 100644
--- a/src/kernel/cpu.h
+++ b/src/kernel/cpu.h
@@ -142,6 +142,8 @@ extern "C" {
     uint64_t set_xcr0(uint64_t val);
 
     cpu_data * _current_gsbase();
+
+    void cpu_initialize_thread_state();
 }
 
 /// Do early initialization of the BSP CPU.
diff --git a/src/kernel/interrupts.cpp b/src/kernel/interrupts.cpp
index 2752dbb..7de3710 100644
--- a/src/kernel/interrupts.cpp
+++ b/src/kernel/interrupts.cpp
@@ -145,6 +145,30 @@ isr_handler(cpu_state *regs)
         }
         break;
 
+    case isr::isrSIMDFPE: {
+            uint32_t mxcsr = 0;
+            asm volatile ("stmxcsr %0" : "=m"(mxcsr));
+            util::format({message, sizeof(message)},
+                "SIMD Exception; MXCSR[%s%s%s%s%s%s%s%s%s%s%s%s%s%s rc:%d]",
+                (mxcsr & 0x0001) ? " IE" : "",
+                (mxcsr & 0x0002) ? " DE" : "",
+                (mxcsr & 0x0004) ? " ZE" : "",
+                (mxcsr & 0x0008) ? " OE" : "",
+                (mxcsr & 0x0010) ? " UE" : "",
+                (mxcsr & 0x0020) ? " PE" : "",
+                (mxcsr & 0x0040) ? " DAZ" : "",
+                (mxcsr & 0x0080) ? " IM" : "",
+                (mxcsr & 0x0100) ? " DM" : "",
+                (mxcsr & 0x0200) ? " ZM" : "",
+                (mxcsr & 0x0400) ? " OM" : "",
+                (mxcsr & 0x0800) ? " UM" : "",
+                (mxcsr & 0x1000) ? " PM" : "",
+                (mxcsr & 0x8000) ? " FTZ" : "",
+                ((mxcsr >> 13) & 0x3));
+            kassert(false, message, regs);
+        }
+        break;
+ 
     case isr::isrSpurious:
         // No EOI for the spurious interrupt
         return;
diff --git a/src/kernel/objects/thread.cpp b/src/kernel/objects/thread.cpp
index 1a58f2f..9475092 100644
--- a/src/kernel/objects/thread.cpp
+++ b/src/kernel/objects/thread.cpp
@@ -34,6 +34,15 @@ thread::thread(process &parent, uint8_t pri, uintptr_t rsp0) :
         m_tcb.rsp0 = rsp0;
 
     m_creator = current_cpu().thread;
+
+    asm volatile ( "stmxcsr %0" : "=m"(m_mxcsr) );
+    m_mxcsr
+        .clear(mxcsr::IE)
+        .clear(mxcsr::DE)
+        .clear(mxcsr::ZE)
+        .clear(mxcsr::OE)
+        .clear(mxcsr::UE)
+        .clear(mxcsr::PE);
 }
 
 thread::~thread()
diff --git a/src/kernel/objects/thread.h b/src/kernel/objects/thread.h
index 52c685a..150afa9 100644
--- a/src/kernel/objects/thread.h
+++ b/src/kernel/objects/thread.h
@@ -7,10 +7,10 @@
 #include <util/linked_list.h>
 #include <util/spinlock.h>
 
+#include "cpu.h"
 #include "objects/kobject.h"
 #include "wait_queue.h"
 
-struct cpu_data;
 struct page_table;
 
 namespace obj {
@@ -176,6 +176,7 @@ private:
     thread(const thread &other) = delete;
     thread(const thread &&other) = delete;
     friend class process;
+    friend void ::cpu_initialize_thread_state();
 
     /// Constructor. Used when a kernel stack already exists.
     /// \arg parent  The process which owns this thread
@@ -195,6 +196,7 @@ private:
     thread *m_creator;
 
     state m_state;
+    util::bitset32 m_mxcsr;
 
     uint64_t m_wake_value;
     uint64_t m_wake_timeout;
diff --git a/src/kernel/syscall.s b/src/kernel/syscall.s
index f27eea3..47d1dab 100644
--- a/src/kernel/syscall.s
+++ b/src/kernel/syscall.s
@@ -16,10 +16,11 @@ STAR_HIGH  equ \
 ; IA32_FMASK - Mask off interrupts in syscalls
 FMASK_VAL  equ 0x200
 
-extern __counter_syscall_enter
-extern __counter_syscall_sysret
-extern syscall_registry
-extern syscall_invalid
+extern __counter_syscall_enter          ; syscall.cpp.cog
+extern __counter_syscall_sysret         ;
+extern syscall_registry                 ;
+extern syscall_invalid                  ;
+extern cpu_initialize_thread_state      ; cpu.cpp
 
 
 global syscall_handler_prelude: function hidden (syscall_handler_prelude.end - syscall_handler_prelude)
@@ -79,6 +80,8 @@ syscall_handler_prelude:
 
 global initialize_user_cpu: function hidden (initialize_user_cpu.end - initialize_user_cpu)
 initialize_user_cpu:
+    call cpu_initialize_thread_state
+
     mov rax, 0xaaaaaaaa
     mov rdx, 0xdddddddd
     mov r8,  0x08080808
diff --git a/src/libraries/util/util/bitset.h b/src/libraries/util/util/bitset.h
index 685dfaa..27a2d34 100644
--- a/src/libraries/util/util/bitset.h
+++ b/src/libraries/util/util/bitset.h
@@ -66,8 +66,6 @@ namespace {
 template <>
 class bitset<64>
 {
-    static constexpr unsigned num_elems = 1;
-
     template <typename T>
     static constexpr uint64_t bit_or(T b) { return 1ull << uint64_t(b); }
 
@@ -127,8 +125,6 @@ private:
 template <>
 class bitset<32>
 {
-    static constexpr unsigned num_elems = 1;
-
     template <typename T>
     static constexpr uint32_t bit_or(T b) { return 1u << uint32_t(b); }