diff --git a/Ports/ARM-Cortex-M/ARMv7-M/ARM/os_cpu_a.asm b/Ports/ARM-Cortex-M/ARMv7-M/ARM/os_cpu_a.asm
index 352fb8e..9c1d849 100644
--- a/Ports/ARM-Cortex-M/ARMv7-M/ARM/os_cpu_a.asm
+++ b/Ports/ARM-Cortex-M/ARMv7-M/ARM/os_cpu_a.asm
@@ -361,7 +361,11 @@ OS_CPU_PendSVHandler
     MSR     PSP, R0                                             ; Load PSP with new process SP
 
     MOV32   R2, #0                                              ; Restore BASEPRI priority level to 0
+    CPSID   I
     MSR     BASEPRI, R2
+    DSB
+    ISB
+    CPSIE   I
     BX      LR                                                  ; Exception return will restore remaining context
 
     ALIGN                                                       ; Removes warning[A1581W]: added <no_padbytes> of padding at <address>
diff --git a/Ports/ARM-Cortex-M/ARMv7-M/CCS/os_cpu_a.asm b/Ports/ARM-Cortex-M/ARMv7-M/CCS/os_cpu_a.asm
index 966c67f..81e244d 100644
--- a/Ports/ARM-Cortex-M/ARMv7-M/CCS/os_cpu_a.asm
+++ b/Ports/ARM-Cortex-M/ARMv7-M/CCS/os_cpu_a.asm
@@ -382,7 +382,11 @@ OS_CPU_PendSVHandler:
     MSR     PSP, R0                                             ; Load PSP with new process SP
 
     MOV     R2, #0                                              ; Restore BASEPRI priority level to 0
+    CPSID   I
     MSR     BASEPRI, R2
+    DSB
+    ISB
+    CPSIE   I
     BX      LR                                                  ; Exception return will restore remaining context
     .endasmfunc
 
diff --git a/Ports/ARM-Cortex-M/ARMv7-M/GNU/os_cpu_a.S b/Ports/ARM-Cortex-M/ARMv7-M/GNU/os_cpu_a.S
index bcc1a26..c7082f3 100644
--- a/Ports/ARM-Cortex-M/ARMv7-M/GNU/os_cpu_a.S
+++ b/Ports/ARM-Cortex-M/ARMv7-M/GNU/os_cpu_a.S
@@ -379,7 +379,11 @@ OS_CPU_PendSVHandler:
     MSR     PSP, R0                                             @ Load PSP with new process SP
 
     MOV     R2, #0                                              @ Restore BASEPRI priority level to 0
+    CPSID   I
     MSR     BASEPRI, R2
+    DSB
+    ISB
+    CPSIE   I
     BX      LR                                                  @ Exception return will restore remaining context
 
 .end
diff --git a/Ports/ARM-Cortex-M/ARMv7-M/IAR/os_cpu_a.asm b/Ports/ARM-Cortex-M/ARMv7-M/IAR/os_cpu_a.asm
index 36df763..13bf1a8 100644
--- a/Ports/ARM-Cortex-M/ARMv7-M/IAR/os_cpu_a.asm
+++ b/Ports/ARM-Cortex-M/ARMv7-M/IAR/os_cpu_a.asm
@@ -355,7 +355,11 @@ OS_CPU_PendSVHandler
     MSR     PSP, R0                                             ; Load PSP with new process SP
 
     MOV32   R2, #0                                              ; Restore BASEPRI priority level to 0
+    CPSID   I
     MSR     BASEPRI, R2
+    DSB
+    ISB
+    CPSIE   I
     BX      LR                                                  ; Exception return will restore remaining context
 
     END