diff --git a/src/soc/amd/common/block/cpu/Kconfig b/src/soc/amd/common/block/cpu/Kconfig
index 857c8cba53..03a3b7295b 100644
--- a/src/soc/amd/common/block/cpu/Kconfig
+++ b/src/soc/amd/common/block/cpu/Kconfig
@@ -35,7 +35,7 @@ config CBFS_CACHE_SIZE
 
 config ACPI_CPU_STRING
 	string
-	default "C%03d"
+	default "C%03X"
 
 endif # SOC_AMD_COMMON_BLOCK_NONCAR
 
diff --git a/src/soc/amd/stoneyridge/Kconfig b/src/soc/amd/stoneyridge/Kconfig
index f57111d863..1e35d766af 100644
--- a/src/soc/amd/stoneyridge/Kconfig
+++ b/src/soc/amd/stoneyridge/Kconfig
@@ -268,7 +268,7 @@ config SMM_MODULE_STACK_SIZE
 
 config ACPI_CPU_STRING
 	string
-	default "P%03d"
+	default "P%03X"
 
 config ACPI_SSDT_PSD_INDEPENDENT
 	default n