diff --git a/src/clang_tu.cc b/src/clang_tu.cc
index f147b4c2..b58a69e9 100644
--- a/src/clang_tu.cc
+++ b/src/clang_tu.cc
@@ -22,8 +22,6 @@ limitations under the License.
 #include <clang/Lex/Lexer.h>
 #include <llvm/Support/Path.h>
 
-#include <mutex>
-
 using namespace clang;
 
 std::string PathFromFileEntry(const FileEntry &file) {
diff --git a/src/config.h b/src/config.h
index 8889f94b..32d9fff6 100644
--- a/src/config.h
+++ b/src/config.h
@@ -130,6 +130,9 @@ struct Config {
     // that implement their own filtering and sorting logic.
     bool filterAndSort = true;
 
+    // Maxmum number of results.
+    int maxNum = 100;
+
     struct Include {
       // Regex patterns to match include completion candidates against. They
       // receive the absolute file path.
@@ -260,7 +263,8 @@ MAKE_REFLECT_STRUCT(Config::CodeLens, localVariables);
 MAKE_REFLECT_STRUCT(Config::Completion::Include, blacklist, maxPathSize,
                     suffixWhitelist, whitelist);
 MAKE_REFLECT_STRUCT(Config::Completion, caseSensitivity, detailedLabel,
-                    dropOldRequests, duplicateOptional, filterAndSort, include);
+                    dropOldRequests, duplicateOptional, filterAndSort, include,
+                    maxNum);
 MAKE_REFLECT_STRUCT(Config::Diagnostics, blacklist, onChange, onOpen, onSave,
                     spellChecking, whitelist)
 MAKE_REFLECT_STRUCT(Config::Highlight, largeFileSize, lsRanges, blacklist,
diff --git a/src/messages/textDocument_completion.cc b/src/messages/textDocument_completion.cc
index 411e4763..daa6c7c3 100644
--- a/src/messages/textDocument_completion.cc
+++ b/src/messages/textDocument_completion.cc
@@ -182,9 +182,9 @@ void FilterAndSortCompletionResponse(
   auto &items = complete_response->result.items;
 
   auto finalize = [&]() {
-    const size_t kMaxResultSize = 100u;
-    if (items.size() > kMaxResultSize) {
-      items.resize(kMaxResultSize);
+    int max_num = g_config->completion.maxNum;
+    if (items.size() > max_num) {
+      items.resize(max_num);
       complete_response->result.isIncomplete = true;
     }