diff --git a/base/common/LineReader.cpp b/base/common/LineReader.cpp
index c69690e3420..816184fdb1f 100644
--- a/base/common/LineReader.cpp
+++ b/base/common/LineReader.cpp
@@ -52,19 +52,10 @@ LineReader::Suggest::WordsRange LineReader::Suggest::getCompletions(const String
         last_word = std::string_view(prefix).substr(last_word_pos + 1, std::string::npos);
 
     /// last_word can be empty.
-
-    if (case_insensitive)
-        return std::equal_range(
-                words.begin(), words.end(), last_word, [prefix_length](std::string_view s, std::string_view prefix_searched)
-                {
-                    return strncasecmp(s.data(), prefix_searched.data(), prefix_length) < 0;
-                });
-    else
-        return std::equal_range(
-                words.begin(), words.end(), last_word, [prefix_length](std::string_view s, std::string_view prefix_searched)
-                {
-                    return strncmp(s.data(), prefix_searched.data(), prefix_length) < 0;
-                });
+    return std::equal_range(words.begin(), words.end(), last_word, [prefix_length](std::string_view s, std::string_view prefix_searched)
+    {
+        return strncasecmp(s.data(), prefix_searched.data(), prefix_length) < 0;
+    });
 }
 
 LineReader::LineReader(const String & history_file_path_, char extender_, char delimiter_)
diff --git a/base/common/LineReader.h b/base/common/LineReader.h
index 66de46d5fcb..06f737a860b 100644
--- a/base/common/LineReader.h
+++ b/base/common/LineReader.h
@@ -18,9 +18,6 @@ public:
 
         /// Get iterators for the matched range of words if any.
         WordsRange getCompletions(const String & prefix, size_t prefix_length) const;
-
-        /// case sensitive suggestion
-        bool case_insensitive = false;
     };
 
     LineReader(const String & history_file_path, char extender, char delimiter = 0);  /// if delimiter != 0, then it's multiline mode
diff --git a/dbms/programs/client/Client.cpp b/dbms/programs/client/Client.cpp
index 4885b08ad91..0618e6272d6 100644
--- a/dbms/programs/client/Client.cpp
+++ b/dbms/programs/client/Client.cpp
@@ -481,8 +481,6 @@ private:
 
             if (server_revision >= Suggest::MIN_SERVER_REVISION && !config().getBool("disable_suggestion", false))
             {
-                if (config().has("case_insensitive_suggestion"))
-                    Suggest::instance().setCaseInsensitive();
                 /// Load suggestion data from the server.
                 Suggest::instance().load(connection_parameters, config().getInt("suggestion_limit"));
             }
@@ -1720,7 +1718,6 @@ public:
             ("always_load_suggestion_data", "Load suggestion data even if clickhouse-client is run in non-interactive mode. Used for testing.")
             ("suggestion_limit", po::value<int>()->default_value(10000),
                 "Suggestion limit for how many databases, tables and columns to fetch.")
-            ("case_insensitive_suggestion", "Case sensitive suggestions.")
             ("multiline,m", "multiline")
             ("multiquery,n", "multiquery")
             ("format,f", po::value<std::string>(), "default output format")
diff --git a/dbms/programs/client/Suggest.cpp b/dbms/programs/client/Suggest.cpp
index 9058bafd138..528e8d74a2b 100644
--- a/dbms/programs/client/Suggest.cpp
+++ b/dbms/programs/client/Suggest.cpp
@@ -50,16 +50,13 @@ void Suggest::load(const ConnectionParameters & connection_parameters, size_t su
 
         /// Note that keyword suggestions are available even if we cannot load data from server.
 
-        if (case_insensitive)
-            std::sort(words.begin(), words.end(), [](const std::string & str1, const std::string & str2)
+        std::sort(words.begin(), words.end(), [](const std::string & str1, const std::string & str2)
+        {
+            return std::lexicographical_compare(begin(str1), end(str1), begin(str2), end(str2), [](const char char1, const char char2)
             {
-                return std::lexicographical_compare(begin(str1), end(str1), begin(str2), end(str2), [](const char char1, const char char2)
-                {
-                    return std::tolower(char1) < std::tolower(char2);
-                });
+                return std::tolower(char1) < std::tolower(char2);
             });
-        else
-            std::sort(words.begin(), words.end());
+        });
 
         ready = true;
     });
diff --git a/dbms/programs/client/Suggest.h b/dbms/programs/client/Suggest.h
index a4d357d09b3..6c81a388ea7 100644
--- a/dbms/programs/client/Suggest.h
+++ b/dbms/programs/client/Suggest.h
@@ -23,9 +23,6 @@ public:
         return instance;
     }
 
-    /// Need to set before load
-    void setCaseInsensitive() { case_insensitive = true; }
-
     void load(const ConnectionParameters & connection_parameters, size_t suggestion_limit);
 
     /// Older server versions cannot execute the query above.