diff --git a/httplib.h b/httplib.h
index 8967012..99ca369 100644
--- a/httplib.h
+++ b/httplib.h
@@ -781,11 +781,13 @@ inline const char *get_header_value(const Headers &headers, const char *key,
   return def;
 }
 
-inline int get_header_value_int(const Headers &headers, const char *key,
-                                int def = 0) {
-  auto it = headers.find(key);
-  if (it != headers.end()) { return std::stoi(it->second); }
-  return def;
+inline uint64_t get_header_value_uint64(const Headers &headers, const char *key,
+								int def = 0) {
+	auto it = headers.find(key);
+	if (it != headers.end()) {
+		return std::strtoull(it->second.data(), nullptr, 10);
+	}
+	return def;
 }
 
 inline bool read_headers(Stream &strm, Headers &headers) {
@@ -881,7 +883,7 @@ inline bool read_content_chunked(Stream &strm, std::string &out) {
 template <typename T>
 bool read_content(Stream &strm, T &x, Progress progress = Progress()) {
   if (has_header(x.headers, "Content-Length")) {
-    auto len = get_header_value_int(x.headers, "Content-Length", 0);
+    auto len = get_header_value_uint64(x.headers, "Content-Length", 0);
     if (len == 0) {
       const auto &encoding =
           get_header_value(x.headers, "Transfer-Encoding", 0, "");
diff --git a/test/test.cc b/test/test.cc
index 0143e62..deb6f6d 100644
--- a/test/test.cc
+++ b/test/test.cc
@@ -72,8 +72,8 @@ TEST(GetHeaderValueTest, DefaultValue) {
 
 TEST(GetHeaderValueTest, DefaultValueInt) {
   Headers headers = {{"Dummy", "Dummy"}};
-  auto val = detail::get_header_value_int(headers, "Content-Length", 100);
-  EXPECT_EQ(100, val);
+  auto val = detail::get_header_value_uint64(headers, "Content-Length", 100);
+  EXPECT_EQ(100ull, val);
 }
 
 TEST(GetHeaderValueTest, RegularValue) {
@@ -84,8 +84,8 @@ TEST(GetHeaderValueTest, RegularValue) {
 
 TEST(GetHeaderValueTest, RegularValueInt) {
   Headers headers = {{"Content-Length", "100"}, {"Dummy", "Dummy"}};
-  auto val = detail::get_header_value_int(headers, "Content-Length", 0);
-  EXPECT_EQ(100, val);
+  auto val = detail::get_header_value_uint64(headers, "Content-Length", 0);
+  EXPECT_EQ(100ull, val);
 }
 
 TEST(GetHeaderValueTest, Range) {
@@ -474,7 +474,7 @@ protected:
                EXPECT_EQ("value3", req.get_param_value("array", 2));
              })
         .Post("/validate-no-multiple-headers",
-              [&](const Request &req, Response &res) {
+              [&](const Request &req, Response & /*res*/) {
                 EXPECT_EQ(1u, req.get_header_value_count("Content-Length"));
                 EXPECT_EQ("5", req.get_header_value("Content-Length"));
               })