diff --git a/os/rt/ports/ARMCMx/chcore_v6m.h b/os/rt/ports/ARMCMx/chcore_v6m.h
index ed05fe6b7..e70c9b61c 100644
--- a/os/rt/ports/ARMCMx/chcore_v6m.h
+++ b/os/rt/ports/ARMCMx/chcore_v6m.h
@@ -395,7 +395,7 @@ static inline void port_enable(void) {
 static inline void port_wait_for_interrupt(void) {
 
 #if CORTEX_ENABLE_WFI_IDLE
-  __WFI;
+  __WFI();
 #endif
 }
 
diff --git a/os/rt/ports/ARMCMx/chcore_v7m.h b/os/rt/ports/ARMCMx/chcore_v7m.h
index 404e87411..728b770e7 100644
--- a/os/rt/ports/ARMCMx/chcore_v7m.h
+++ b/os/rt/ports/ARMCMx/chcore_v7m.h
@@ -534,7 +534,7 @@ static inline void port_enable(void) {
 static inline void port_wait_for_interrupt(void) {
 
 #if CORTEX_ENABLE_WFI_IDLE
-  __WFI;
+  __WFI();
 #endif
 }