diff --git a/MdeModulePkg/Universal/RegularExpressionDxe/Oniguruma/reggnu.c b/MdeModulePkg/Universal/RegularExpressionDxe/Oniguruma/reggnu.c
index 70746794a0..f9af9ca93c 100644
--- a/MdeModulePkg/Universal/RegularExpressionDxe/Oniguruma/reggnu.c
+++ b/MdeModulePkg/Universal/RegularExpressionDxe/Oniguruma/reggnu.c
@@ -151,15 +151,6 @@ re_mbcinit(int mb_code)
   case RE_MBCTYPE_ASCII:
     enc = ONIG_ENCODING_ASCII;
     break;
-  case RE_MBCTYPE_EUC:
-    enc = ONIG_ENCODING_EUC_JP;
-    break;
-  case RE_MBCTYPE_SJIS:
-    enc = ONIG_ENCODING_SJIS;
-    break;
-  case RE_MBCTYPE_UTF8:
-    enc = ONIG_ENCODING_UTF8;
-    break;
   default:
     return;
   }
diff --git a/MdeModulePkg/Universal/RegularExpressionDxe/Oniguruma/regposix.c b/MdeModulePkg/Universal/RegularExpressionDxe/Oniguruma/regposix.c
index cd294cd9e5..299b88c6cc 100644
--- a/MdeModulePkg/Universal/RegularExpressionDxe/Oniguruma/regposix.c
+++ b/MdeModulePkg/Universal/RegularExpressionDxe/Oniguruma/regposix.c
@@ -238,18 +238,6 @@ reg_set_encoding(int mb_code)
   case REG_POSIX_ENCODING_ASCII:
     enc = ONIG_ENCODING_ASCII;
     break;
-  case REG_POSIX_ENCODING_EUC_JP:
-    enc = ONIG_ENCODING_EUC_JP;
-    break;
-  case REG_POSIX_ENCODING_SJIS:
-    enc = ONIG_ENCODING_SJIS;
-    break;
-  case REG_POSIX_ENCODING_UTF8:
-    enc = ONIG_ENCODING_UTF8;
-    break;
-  case REG_POSIX_ENCODING_UTF16_BE:
-    enc = ONIG_ENCODING_UTF16_BE;
-    break;
   case REG_POSIX_ENCODING_UTF16_LE:
     enc = ONIG_ENCODING_UTF16_LE;
     break;