diff --git a/src/host/pico_multicore/include/pico/multicore.h b/src/host/pico_multicore/include/pico/multicore.h
index de6672a..f4d8364 100644
--- a/src/host/pico_multicore/include/pico/multicore.h
+++ b/src/host/pico_multicore/include/pico/multicore.h
@@ -13,29 +13,28 @@
 extern "C" {
 #endif
 
-void multicore_reset_core1();
+void multicore_reset_core1(void);
 void multicore_launch_core1(void (*entry)(void));
 void multicore_launch_core1_with_stack(void (*entry)(void), uint32_t *stack_bottom, size_t stack_size_bytes);
-void multicore_sleep_core1();
 void multicore_launch_core1_raw(void (*entry)(void), uint32_t *sp, uint32_t vector_table);
 
-bool multicore_fifo_rvalid();
-bool multicore_fifo_wready();
+bool multicore_fifo_rvalid(void);
+bool multicore_fifo_wready(void);
 void multicore_fifo_push(uint32_t data);
 uint32_t multicore_fifo_pop_blocking();
-void multicore_fifo_drain();
-void multicore_fifo_clear_irq();
-int32_t multicore_fifo_get_status();
+void multicore_fifo_drain(void);
+void multicore_fifo_clear_irq(void);
+int32_t multicore_fifo_get_status(void);
 
 // call this from the lockout victim thread
-void multicore_lockout_victim_init();
+void multicore_lockout_victim_init(void);
 
 // start locking out the other core (it will be
 bool multicore_lockout_start_timeout_us(uint64_t timeout_us);
-void multicore_lockout_start_blocking();
+void multicore_lockout_start_blocking(void);
 
 bool multicore_lockout_end_timeout_us(uint64_t timeout_us);
-void multicore_lockout_end_blocking();
+void multicore_lockout_end_blocking(void);
 
 #ifdef __cplusplus
 }
diff --git a/src/rp2_common/pico_multicore/include/pico/multicore.h b/src/rp2_common/pico_multicore/include/pico/multicore.h
index 8738641..3d52654 100644
--- a/src/rp2_common/pico_multicore/include/pico/multicore.h
+++ b/src/rp2_common/pico_multicore/include/pico/multicore.h
@@ -55,12 +55,6 @@ void multicore_launch_core1(void (*entry)(void));
  */
 void multicore_launch_core1_with_stack(void (*entry)(void), uint32_t *stack_bottom, size_t stack_size_bytes);
 
-/*! \brief  Send core 1 to sleep.
- *  \ingroup pico_multicore
- *
- */
-void multicore_sleep_core1(void);
-
 /*! \brief  Launch code on core 1 with no stack protection
  *  \ingroup pico_multicore
  *
diff --git a/src/rp2_common/pico_multicore/multicore.c b/src/rp2_common/pico_multicore/multicore.c
index fa4f49e..0033bcf 100644
--- a/src/rp2_common/pico_multicore/multicore.c
+++ b/src/rp2_common/pico_multicore/multicore.c
@@ -107,15 +107,6 @@ void multicore_reset_core1() {
     *power_off_clr = PSM_FRCE_OFF_PROC1_BITS;
 }
 
-void multicore_sleep_core1() {
-    multicore_reset_core1();
-    // note we give core1 an invalid stack pointer, as it should not be used
-    // note also if we ge simply passed a function that returned immediately, we'd end up in core1_hang anyway
-    //  however that would waste 2 bytes for that function (the horror!)
-    extern void core1_hang(void); // in crt0.S
-    multicore_launch_core1_raw(core1_hang, (uint32_t *) -1, scb_hw->vtor);
-}
-
 void multicore_launch_core1_with_stack(void (*entry)(void), uint32_t *stack_bottom, size_t stack_size_bytes) {
     assert(!(stack_size_bytes & 3u));
     uint32_t *stack_ptr = stack_bottom + stack_size_bytes / sizeof(uint32_t);