diff --git a/src/getProvinceCode.js b/src/getProvinceCode.js
index f3c2d77..2f2bb6d 100644
--- a/src/getProvinceCode.js
+++ b/src/getProvinceCode.js
@@ -19,7 +19,7 @@ function getProvinceCode(value) {
 
   const [code] = _partsOld(str);
 
-  return PROVINCES[code] ? code : null;
+  return code ? (PROVINCES[code.toUpperCase()] ? code.toUpperCase() : null) : null;
 }
 
 export { getProvinceCode };
diff --git a/src/getProvinceName.js b/src/getProvinceName.js
index 0be8596..1b2b18e 100644
--- a/src/getProvinceName.js
+++ b/src/getProvinceName.js
@@ -13,7 +13,7 @@ function getProvinceName(value) {
   const str = !value ? "" : value;
   const code = getProvinceCode(str);
 
-  return PROVINCES[code] || null;
+  return code ? PROVINCES[code.toUpperCase()] : null;
 }
 
 export { getProvinceName };