diff --git a/os/common/ports/ARMv8-M-ML/chcore.h b/os/common/ports/ARMv8-M-ML/chcore.h
index 8e909cb42..c2d455f29 100644
--- a/os/common/ports/ARMv8-M-ML/chcore.h
+++ b/os/common/ports/ARMv8-M-ML/chcore.h
@@ -511,7 +511,7 @@ struct port_context {
 #else
   #define port_switch(ntp, otp) do {                                        \
     struct port_intctx *r13 = (struct port_intctx *)__get_PSP();            \
-    if ((stkalign_t *)(r13 - 1) < (otp)->wabase) {                          \
+    if ((stkalign_t *)(void *)(r13 - 1) < (otp)->wabase) {                  \
       chSysHalt("stack overflow");                                          \
     }                                                                       \
     __port_switch(ntp, otp);                                                \