diff --git a/DynamicTablesPkg/Include/Library/AcpiHelperLib.h b/DynamicTablesPkg/Include/Library/AcpiHelperLib.h
index 2731a2e4fb..53ab19b1d1 100644
--- a/DynamicTablesPkg/Include/Library/AcpiHelperLib.h
+++ b/DynamicTablesPkg/Include/Library/AcpiHelperLib.h
@@ -22,15 +22,16 @@
 
 /** Convert a hex number to its ASCII code.
 
- @param [in]  x   Hex number to convert.
-                  Must be 0 <= x < 16.
+ @param [in]  Hex   Hex number to convert.
+                    Must be 0 <= x < 16.
 
  @return The ASCII code corresponding to x.
+         -1 if error.
 **/
 UINT8
 EFIAPI
 AsciiFromHex (
-  IN  UINT8   x
+  IN  UINT8   Hex
   );
 
 /** Check if a HID is a valid PNP ID.
diff --git a/DynamicTablesPkg/Library/Common/AcpiHelperLib/AcpiHelper.c b/DynamicTablesPkg/Library/Common/AcpiHelperLib/AcpiHelper.c
index 85a32269aa..434b472cbb 100644
--- a/DynamicTablesPkg/Library/Common/AcpiHelperLib/AcpiHelper.c
+++ b/DynamicTablesPkg/Library/Common/AcpiHelperLib/AcpiHelper.c
@@ -14,23 +14,24 @@
 
 /** Convert a hex number to its ASCII code.
 
- @param [in]  x   Hex number to convert.
-                  Must be 0 <= x < 16.
+ @param [in]  Hex   Hex number to convert.
+                    Must be 0 <= x < 16.
 
  @return The ASCII code corresponding to x.
+         -1 if error.
 **/
 UINT8
 EFIAPI
 AsciiFromHex (
-  IN  UINT8   x
+  IN  UINT8   Hex
   )
 {
-  if (x < 10) {
-    return (UINT8)(x + '0');
+  if (Hex < 10) {
+    return (UINT8)(Hex + '0');
   }
 
-  if (x < 16) {
-    return (UINT8)(x - 10 + 'A');
+  if (Hex < 16) {
+    return (UINT8)(Hex - 10 + 'A');
   }
 
   ASSERT (FALSE);