diff --git a/kernel/arch/arm/cortex-m4/iar/los_dispatch.S b/kernel/arch/arm/cortex-m4/iar/los_dispatch.S
index 70d1c81d..cbb3fd44 100644
--- a/kernel/arch/arm/cortex-m4/iar/los_dispatch.S
+++ b/kernel/arch/arm/cortex-m4/iar/los_dispatch.S
@@ -41,6 +41,8 @@
         IMPORT  g_losTask
         IMPORT  g_taskScheduled
 
+OS_FPU_CPACR                EQU     0xE000ED88
+OS_FPU_CPACR_ENABLE         EQU     0x00F00000
 OS_NVIC_INT_CTRL            EQU     0xE000ED04
 OS_NVIC_SYSPRI2             EQU     0xE000ED20
 OS_NVIC_PENDSV_PRI          EQU     0xF0F00000
@@ -77,8 +79,11 @@ HalStartToRun
     STRH    R7,  [R0 , #4]
 
     LDR     R12, [R0]
-#if ((defined(__FPU_PRESENT) && (__FPU_PRESENT == 1U)) && \
-     (defined(__FPU_USED) && (__FPU_USED == 1U)))
+
+    LDR.W   R1, =OS_FPU_CPACR
+    LDR     R1, [R1]
+    AND     R1, R1, #OS_FPU_CPACR_ENABLE
+    BNE     __DisabledFPU
     ADD     R12, R12, #100
 
     LDMFD   R12!, {R0-R7}
@@ -86,15 +91,16 @@ HalStartToRun
     MSR     PSP, R12
     VPUSH   S0;
     VPOP    S0;
-#else
+    MOV     LR, R5
+    CPSIE   I
+    BX      R6
+
+__DisabledFPU
     ADD     R12, R12, #36
 
     LDMFD   R12!, {R0-R7}
     MSR     PSP, R12
-#endif
     MOV     LR, R5
-   ;MSR     xPSR, R7
-
     CPSIE   I
     BX      R6
 
@@ -127,11 +133,13 @@ HalTaskSwitch
     MRS     R0, PSP
 
     STMFD   R0!, {R4-R12}
-#if ((defined(__FPU_PRESENT) && (__FPU_PRESENT == 1U)) && \
-     (defined(__FPU_USED) && (__FPU_USED == 1U)))
+    LDR.W   R3, =OS_FPU_CPACR
+    LDR     R3, [R3]
+    AND     R3, R3, #OS_FPU_CPACR_ENABLE
+    BNE     __DisabledFPU1
     VSTMDB  R0!, {D8-D15}
-#endif
 
+__DisabledFPU1
     LDR     R5, =g_losTask
     LDR     R6, [R5]
     STR     R0, [R6]
@@ -154,10 +162,11 @@ HalTaskSwitch
     STRH    R7,  [R0 , #4]
 
     LDR     R1,   [R0]
-#if ((defined(__FPU_PRESENT) && (__FPU_PRESENT == 1U)) && \
-     (defined(__FPU_USED) && (__FPU_USED == 1U)))
+    AND     R3, R3, #OS_FPU_CPACR_ENABLE
+    BNE     __DisabledFPU2
     VLDMIA  R1!, {D8-D15}
-#endif
+
+__DisabledFPU2
     LDMFD   R1!, {R4-R12}
     MSR     PSP,  R1
 
@@ -165,3 +174,4 @@ HalTaskSwitch
     BX      LR
 
     END
+
diff --git a/kernel/arch/arm/cortex-m4/iar/los_exc.S b/kernel/arch/arm/cortex-m4/iar/los_exc.S
index 653632c0..cb112a49 100644
--- a/kernel/arch/arm/cortex-m4/iar/los_exc.S
+++ b/kernel/arch/arm/cortex-m4/iar/los_exc.S
@@ -198,16 +198,13 @@ _hwiActiveCheck
     ADD   R2, R2, R12, LSL #5               ; calculate R2 (hwi number) as uwPid
 
 _ExcInMSP
-    CMP   LR, #0XFFFFFFED
+    CMP   LR, #0xFFFFFFED
     BNE   _NoFloatInMsp
     ADD   R3, R13, #104
     PUSH  {R3}
     MRS   R12, PRIMASK                  ; store message-->exc: disable int?
     PUSH {R4-R12}                       ; store message-->exc: {R4-R12}
-#if ((defined(__FPU_PRESENT) && (__FPU_PRESENT == 1U)) && \
-     (defined(__FPU_USED) && (__FPU_USED == 1U)))
     VPUSH {D8-D15}
-#endif
     B     _handleEntry
 
 _NoFloatInMsp
diff --git a/targets/cortex-m4_stm32f429ig_fire-challenger_iar/project/los_demo.ewp b/targets/cortex-m4_stm32f429ig_fire-challenger_iar/project/los_demo.ewp
index 6428758e..4f8f4f95 100644
--- a/targets/cortex-m4_stm32f429ig_fire-challenger_iar/project/los_demo.ewp
+++ b/targets/cortex-m4_stm32f429ig_fire-challenger_iar/project/los_demo.ewp
@@ -527,8 +527,7 @@
                 </option>
                 <option>
                     <name>ADefines</name>
-                    <state>__FPU_PRESENT=1</state>
-                    <state>__FPU_USED=1</state>
+                    <state></state>
                 </option>
                 <option>
                     <name>AList</name>