diff --git a/Core/memory.c b/Core/memory.c
index c55b6c6..e10b7bf 100644
--- a/Core/memory.c
+++ b/Core/memory.c
@@ -819,6 +819,8 @@ uint8_t GB_read_memory(GB_gameboy_t *gb, uint16_t addr)
 
 uint8_t GB_safe_read_memory(GB_gameboy_t *gb, uint16_t addr)
 {
+    GB_ASSERT_NOT_RUNNING_OTHER_THREAD(gb)
+
     if (unlikely(addr == 0xFF00 + GB_IO_JOYP)) {
         return gb->io_registers[GB_IO_JOYP];
     }