diff --git a/cc3200/mpthreadport.c b/cc3200/mpthreadport.c
index dd02180982..e77ac4ae53 100644
--- a/cc3200/mpthreadport.c
+++ b/cc3200/mpthreadport.c
@@ -31,8 +31,10 @@
 #include "py/runtime.h"
 #include "py/gc.h"
 #include "py/mpthread.h"
+#include "py/mphal.h"
 #include "mptask.h"
 #include "task.h"
+#include "irq.h"
 
 #if MICROPY_PY_THREAD
 
@@ -166,14 +168,23 @@ void mp_thread_mutex_init(mp_thread_mutex_t *mutex) {
     mutex->handle = xSemaphoreCreateMutexStatic(&mutex->buffer);
 }
 
+// To allow hard interrupts to work with threading we only take/give the semaphore
+// if we are not within an interrupt context and interrupts are enabled.
+
 int mp_thread_mutex_lock(mp_thread_mutex_t *mutex, int wait) {
-    int ret = xSemaphoreTake(mutex->handle, wait ? portMAX_DELAY : 0);
-    return ret == pdTRUE;
+    if ((HAL_NVIC_INT_CTRL_REG & HAL_VECTACTIVE_MASK) == 0 && query_irq() == IRQ_STATE_ENABLED) {
+        int ret = xSemaphoreTake(mutex->handle, wait ? portMAX_DELAY : 0);
+        return ret == pdTRUE;
+    } else {
+        return 1;
+    }
 }
 
 void mp_thread_mutex_unlock(mp_thread_mutex_t *mutex) {
-    xSemaphoreGive(mutex->handle);
-    // TODO check return value
+    if ((HAL_NVIC_INT_CTRL_REG & HAL_VECTACTIVE_MASK) == 0 && query_irq() == IRQ_STATE_ENABLED) {
+        xSemaphoreGive(mutex->handle);
+        // TODO check return value
+    }
 }
 
 #endif // MICROPY_PY_THREAD