diff --git a/README.md b/README.md
index c7a35d417f849aa170a5e98ff97bb549370d01ea..1240a89d951d45f88f55a9fcabcf6bac60e6f1f0 100644
--- a/README.md
+++ b/README.md
@@ -12,7 +12,7 @@ include(FetchContent)
 
 FetchContent_Declare(json
   GIT_REPOSITORY https://github.com/ArthurSonzogni/nlohmann_json_cmake_fetchcontent
-  GIT_TAG v3.9.0)
+  GIT_TAG v3.9.1)
 
 FetchContent_GetProperties(json)
 if(NOT json_POPULATED)
diff --git a/include/nlohmann/json.hpp b/include/nlohmann/json.hpp
index 6a0f47ab44ad734e39523e7681b1712dd3dc4f12..a70aaf8cbcc6e5b5ebb052296dc6015c26f916ec 100644
--- a/include/nlohmann/json.hpp
+++ b/include/nlohmann/json.hpp
@@ -1,7 +1,7 @@
 /*
     __ _____ _____ _____
  __|  |   __|     |   | |  JSON for Modern C++
-|  |  |__   |  |  | | | |  version 3.9.0
+|  |  |__   |  |  | | | |  version 3.9.1
 |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 
 Licensed under the MIT License <http://opensource.org/licenses/MIT>.
@@ -32,7 +32,7 @@ SOFTWARE.
 
 #define NLOHMANN_JSON_VERSION_MAJOR 3
 #define NLOHMANN_JSON_VERSION_MINOR 9
-#define NLOHMANN_JSON_VERSION_PATCH 0
+#define NLOHMANN_JSON_VERSION_PATCH 1
 
 #include <algorithm> // all_of, find, for_each
 #include <cstddef> // nullptr_t, ptrdiff_t, size_t
@@ -6759,13 +6759,13 @@ class lexer : public lexer_base<BasicJsonType>
                                 default:
                                 {
                                     unget();
-                                    break;
+                                    continue;
                                 }
                             }
                         }
 
                         default:
-                            break;
+                            continue;
                     }
                 }
             }
@@ -7390,7 +7390,7 @@ scan_number_done:
         skip_whitespace();
 
         // ignore comments
-        if (ignore_comments && current == '/')
+        while (ignore_comments && current == '/')
         {
             if (!scan_comment())
             {
@@ -16408,6 +16408,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
     using mapped_type = T;
     using Container = std::vector<std::pair<const Key, T>, Allocator>;
     using typename Container::iterator;
+    using typename Container::const_iterator;
     using typename Container::size_type;
     using typename Container::value_type;
 
@@ -16420,7 +16421,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
     ordered_map(std::initializer_list<T> init, const Allocator& alloc = Allocator() )
         : Container{init, alloc} {}
 
-    std::pair<iterator, bool> emplace(key_type&& key, T&& t)
+    std::pair<iterator, bool> emplace(const key_type& key, T&& t)
     {
         for (auto it = this->begin(); it != this->end(); ++it)
         {
@@ -16433,9 +16434,40 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
         return {--this->end(), true};
     }
 
-    T& operator[](Key&& key)
+    T& operator[](const Key& key)
+    {
+        return emplace(key, T{}).first->second;
+    }
+
+    const T& operator[](const Key& key) const
+    {
+        return at(key);
+    }
+
+    T& at(const Key& key)
+    {
+        for (auto it = this->begin(); it != this->end(); ++it)
+        {
+            if (it->first == key)
+            {
+                return it->second;
+            }
+        }
+
+        throw std::out_of_range("key not found");
+    }
+
+    const T& at(const Key& key) const
     {
-        return emplace(std::move(key), T{}).first->second;
+        for (auto it = this->begin(); it != this->end(); ++it)
+        {
+            if (it->first == key)
+            {
+                return it->second;
+            }
+        }
+
+        throw std::out_of_range("key not found");
     }
 
     size_type erase(const Key& key)
@@ -16456,6 +16488,74 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
         }
         return 0;
     }
+
+    iterator erase(iterator pos)
+    {
+        auto it = pos;
+
+        // Since we cannot move const Keys, re-construct them in place
+        for (auto next = it; ++next != this->end(); ++it)
+        {
+            it->~value_type(); // Destroy but keep allocation
+            new (&*it) value_type{std::move(*next)};
+        }
+        Container::pop_back();
+        return pos;
+    }
+
+    size_type count(const Key& key) const
+    {
+        for (auto it = this->begin(); it != this->end(); ++it)
+        {
+            if (it->first == key)
+            {
+                return 1;
+            }
+        }
+        return 0;
+    }
+
+    iterator find(const Key& key)
+    {
+        for (auto it = this->begin(); it != this->end(); ++it)
+        {
+            if (it->first == key)
+            {
+                return it;
+            }
+        }
+        return Container::end();
+    }
+
+    const_iterator find(const Key& key) const
+    {
+        for (auto it = this->begin(); it != this->end(); ++it)
+        {
+            if (it->first == key)
+            {
+                return it;
+            }
+        }
+        return Container::end();
+    }
+
+    std::pair<iterator, bool> insert( value_type&& value )
+    {
+        return emplace(value.first, std::move(value.second));
+    }
+
+    std::pair<iterator, bool> insert( const value_type& value )
+    {
+        for (auto it = this->begin(); it != this->end(); ++it)
+        {
+            if (it->first == value.first)
+            {
+                return {it, false};
+            }
+        }
+        Container::push_back(value);
+        return {--this->end(), true};
+    }
 };
 
 }  // namespace nlohmann
@@ -17440,7 +17540,7 @@ class basic_json
                     object = nullptr;  // silence warning, see #821
                     if (JSON_HEDLEY_UNLIKELY(t == value_t::null))
                     {
-                        JSON_THROW(other_error::create(500, "961c151d2e87f2686a955a9be24d316f1362bf21 3.9.0")); // LCOV_EXCL_LINE
+                        JSON_THROW(other_error::create(500, "961c151d2e87f2686a955a9be24d316f1362bf21 3.9.1")); // LCOV_EXCL_LINE
                     }
                     break;
                 }