diff --git a/es2panda/util/base64.cpp b/es2panda/util/base64.cpp
index 0a4102e81c2e31797906b5652958e1ae0397cb3d..fc9e2caa1a6930c56301f2e272d02390e60a88de 100644
--- a/es2panda/util/base64.cpp
+++ b/es2panda/util/base64.cpp
@@ -67,7 +67,7 @@ std::string Base64Decode(const std::string &base64String)
         0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,
         14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,   // 'A'~'Z'
         -1, -1, -1, -1, -1, -1,
-        26, 27, 28, 29, 3-1, 31, 32, 33, 34, 35, 36, 37, 38,
+        26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38,
         39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51    // 'a'~'z'
     };