diff --git a/MdePkg/Library/BaseLib/AArch64/DisableInterrupts.S b/MdePkg/Library/BaseLib/AArch64/DisableInterrupts.S
index 943cc44c70..9985f1cf68 100644
--- a/MdePkg/Library/BaseLib/AArch64/DisableInterrupts.S
+++ b/MdePkg/Library/BaseLib/AArch64/DisableInterrupts.S
@@ -19,6 +19,8 @@
 .p2align 2
 GCC_ASM_EXPORT(DisableInterrupts)
 
+.set DAIF_WR_IRQ_BIT,   (1 << 1)
+
 #/**
 #  Disables CPU interrupts.
 #
@@ -30,5 +32,5 @@ GCC_ASM_EXPORT(DisableInterrupts)
 #  );
 #
 ASM_PFX(DisableInterrupts):
-   msr  daifset, #2
+   msr  daifset, #DAIF_WR_IRQ_BIT
    ret
diff --git a/MdePkg/Library/BaseLib/AArch64/EnableInterrupts.S b/MdePkg/Library/BaseLib/AArch64/EnableInterrupts.S
index a423102535..cdeff9d73d 100644
--- a/MdePkg/Library/BaseLib/AArch64/EnableInterrupts.S
+++ b/MdePkg/Library/BaseLib/AArch64/EnableInterrupts.S
@@ -19,6 +19,7 @@
 .p2align 2
 GCC_ASM_EXPORT(EnableInterrupts)
 
+.set DAIF_WR_IRQ_BIT,   (1 << 1)
 
 #/**
 #  Enables CPU interrupts.
@@ -31,5 +32,5 @@ GCC_ASM_EXPORT(EnableInterrupts)
 #  );
 #
 ASM_PFX(EnableInterrupts):
-    msr  daifclr, #2
+    msr  daifclr, #DAIF_WR_IRQ_BIT
     ret
diff --git a/MdePkg/Library/BaseLib/AArch64/GetInterruptsState.S b/MdePkg/Library/BaseLib/AArch64/GetInterruptsState.S
index 037f59acef..771299d1d4 100644
--- a/MdePkg/Library/BaseLib/AArch64/GetInterruptsState.S
+++ b/MdePkg/Library/BaseLib/AArch64/GetInterruptsState.S
@@ -19,6 +19,8 @@
 .p2align 2
 GCC_ASM_EXPORT(GetInterruptState)
 
+.set DAIF_RD_IRQ_BIT,   (1 << 7)
+
 #/**
 #  Retrieves the current CPU interrupt state.
 #
@@ -38,8 +40,6 @@ GCC_ASM_EXPORT(GetInterruptState)
 #
 ASM_PFX(GetInterruptState):
     mrs    x0, daif
-    tst    x0, #2            // Check if IRQ is enabled. Enabled if 0.
-    mov    w0, #0
-    mov    w1, #1
-    csel   w0, w1, w0, ne
+    tst    x0, #DAIF_RD_IRQ_BIT   // Check IRQ mask; set Z=1 if clear/unmasked
+    cset   w0, eq                 // if Z=1 (eq) return 1, else 0
     ret