diff --git a/be/src/exprs/encryption_functions.cpp b/be/src/exprs/encryption_functions.cpp
index 52eb5726989fef..ba49c0c7824fe6 100644
--- a/be/src/exprs/encryption_functions.cpp
+++ b/be/src/exprs/encryption_functions.cpp
@@ -181,7 +181,7 @@ StringVal EncryptionFunctions::md5sum(FunctionContext* ctx, int num_args, const
     for (int i = 0; i < num_args; ++i) {
         const StringVal& arg = args[i];
         if (arg.is_null) {
-            continue;
+            return StringVal::null();
         }
         digest.update(arg.ptr, arg.len);
     }
@@ -204,7 +204,7 @@ StringVal EncryptionFunctions::sm3sum(FunctionContext* ctx, int num_args, const
     for (int i = 0; i < num_args; ++i) {
         const StringVal& arg = args[i];
         if (arg.is_null) {
-            continue;
+            return StringVal::null();
         }
         digest.update(arg.ptr, arg.len);
     }