diff --git a/ArmPlatformPkg/ArmJunoPkg/AcpiTables/Madt.aslc b/ArmPlatformPkg/ArmJunoPkg/AcpiTables/Madt.aslc
index d63a19b390..0a167d3ac0 100644
--- a/ArmPlatformPkg/ArmJunoPkg/AcpiTables/Madt.aslc
+++ b/ArmPlatformPkg/ArmJunoPkg/AcpiTables/Madt.aslc
@@ -119,7 +119,8 @@
           0x2C06F000, 0x2C04F000, 25, 0 /* GicRBase */),
     },
     EFI_ACPI_5_0_GIC_DISTRIBUTOR_INIT(0, FixedPcdGet32 (PcdGicDistributorBase), 0),
-    EFI_ACPI_6_0_GIC_MSI_FRAME_INIT(0, ARM_JUNO_GIV2M_MSI_BASE, 0, 0, 0)
+    // Format: EFI_ACPI_6_0_GIC_MSI_FRAME_INIT(GicMsiFrameId, PhysicalBaseAddress, Flags, SPICount, SPIBase)
+    EFI_ACPI_6_0_GIC_MSI_FRAME_INIT(0, ARM_JUNO_GIV2M_MSI_BASE, 0, ARM_JUNO_GIV2M_MSI_SPI_COUNT, ARM_JUNO_GIV2M_MSI_SPI_BASE)
   };
 #endif
 
diff --git a/ArmPlatformPkg/ArmJunoPkg/Include/ArmPlatform.h b/ArmPlatformPkg/ArmJunoPkg/Include/ArmPlatform.h
index 9928c5ae7a..d01d1367f9 100644
--- a/ArmPlatformPkg/ArmJunoPkg/Include/ArmPlatform.h
+++ b/ArmPlatformPkg/ArmJunoPkg/Include/ArmPlatform.h
@@ -40,9 +40,14 @@
 #define ARM_JUNO_PERIPHERALS_BASE             0x20000000
 #define ARM_JUNO_PERIPHERALS_SZ               0x0E000000
 
+// PCIe MSI address window
 #define ARM_JUNO_GIV2M_MSI_BASE               0x2c1c0000
 #define ARM_JUNO_GIV2M_MSI_SZ                 SIZE_256KB
 
+// PCIe MSI to SPI mapping range
+#define ARM_JUNO_GIV2M_MSI_SPI_BASE           224
+#define ARM_JUNO_GIV2M_MSI_SPI_COUNT          127 //TRM says last SPI is 351, 351-224=127
+
 // On-Chip non-secure SRAM
 #define ARM_JUNO_NON_SECURE_SRAM_BASE         0x2E000000
 #define ARM_JUNO_NON_SECURE_SRAM_SZ           SIZE_16MB