diff --git a/ports/stm32f10x/mstimer-init.c b/ports/stm32f10x/mstimer-init.c
index dad6ae89..a4a4563d 100644
--- a/ports/stm32f10x/mstimer-init.c
+++ b/ports/stm32f10x/mstimer-init.c
@@ -48,5 +48,4 @@ void mstimer_init(void)
             /* config error? return  1 = failed, 0 = successful */
         }
     }
-    NVIC_EnableIRQ(SysTick_IRQn);
 }
diff --git a/ports/stm32f4xx/mstimer-init.c b/ports/stm32f4xx/mstimer-init.c
index 045f5f73..660927b0 100644
--- a/ports/stm32f4xx/mstimer-init.c
+++ b/ports/stm32f4xx/mstimer-init.c
@@ -50,5 +50,4 @@ void mstimer_init(void)
             /* config error? return  1 = failed, 0 = successful */
         }
     }
-    NVIC_EnableIRQ(SysTick_IRQn);
 }