diff --git a/dbms/src/IO/tests/valid_utf8.cpp b/dbms/src/IO/tests/valid_utf8.cpp
index ccf176386f9..7033574b99d 100644
--- a/dbms/src/IO/tests/valid_utf8.cpp
+++ b/dbms/src/IO/tests/valid_utf8.cpp
@@ -13,10 +13,10 @@ int main(int argc, char ** argv)
     {
         std::string test1 = "kjhsgdfkjhg2378rtzgvxkz877%^&^*%&^*&*";
         std::string test2 = "{\"asd\" = \"qw1\",\"qwe24\" = \"3asd\"}";
-        test2[test2.find("1")] = char(127 + 64);
-        test2[test2.find("2")] = char(127 + 64 + 32);
-        test2[test2.find("3")] = char(127 + 64 + 32 + 16);
-        test2[test2.find("4")] = char(127 + 64 + 32 + 16 + 8);
+        test2[test2.find('1')] = char(127 + 64);
+        test2[test2.find('2')] = char(127 + 64 + 32);
+        test2[test2.find('3')] = char(127 + 64 + 32 + 16);
+        test2[test2.find('4')] = char(127 + 64 + 32 + 16 + 8);
 
         std::string str;
         {
diff --git a/dbms/src/Storages/tests/seek_speed_test.cpp b/dbms/src/Storages/tests/seek_speed_test.cpp
index bb06f7b95bf..3d5e8bcc6d2 100644
--- a/dbms/src/Storages/tests/seek_speed_test.cpp
+++ b/dbms/src/Storages/tests/seek_speed_test.cpp
@@ -33,7 +33,7 @@ int main(int argc, const char ** argv)
     UInt64 size = Poco::File(argv[1]).getSize();
     UInt64 pos = 0;
     DB::ReadBufferFromFile in(argv[1], buf_size);
-    char * buf = new char[block];
+    auto buf = std::make_unique<char[]>(block);
     int checksum = 0;
     UInt64 bytes_read = 0;