diff --git a/.appveyor.yml b/.appveyor.yml
index 27089cb..4f3132d 100644
--- a/.appveyor.yml
+++ b/.appveyor.yml
@@ -1,7 +1,6 @@
 version: "{build}"
 shallow_clone: true
 image:
-  - Visual Studio 2015
   - Visual Studio 2017
   - Visual Studio 2019 Preview
 platform:
diff --git a/.travis.yml b/.travis.yml
index 1a7301c..739cd3b 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -9,14 +9,6 @@ matrix:
       dist: trusty
       addons: { apt: { sources: ubuntu-toolchain-r-test, packages: ["xorg-dev", "g++-8"] } }
       env: MATRIX_EVAL="CC=gcc-8 && CXX=g++-8"
-    - os: linux
-      dist: trusty
-      addons: { apt: { sources: ["ubuntu-toolchain-r-test", "llvm-toolchain-trusty-5.0"], packages: ["xorg-dev", "clang-5.0", "g++-7"] } }
-      env: MATRIX_EVAL="CC=clang-5.0 && CXX=clang++-5.0"
-    - os: linux
-      dist: trusty
-      addons: { apt: { sources: ["ubuntu-toolchain-r-test", "llvm-toolchain-trusty-6.0"], packages: ["xorg-dev", "clang-6.0", "g++-7"] } }
-      env: MATRIX_EVAL="CC=clang-6.0 && CXX=clang++-6.0"
     - os: linux
       dist: trusty
       addons: { apt: { sources: ["ubuntu-toolchain-r-test", "llvm-toolchain-trusty-7"], packages: ["xorg-dev", "clang-7", "g++-7"] } }
diff --git a/README.md b/README.md
index 95f119c..eddf500 100644
--- a/README.md
+++ b/README.md
@@ -183,6 +183,7 @@ void clear();
 iterator erase(const_iterator iter);
 iterator erase(const_iterator first, const_iterator last);
 size_type erase(const key_type& key);
+template < typename K > size_type erase(const K& key);
 
 void swap(flat_set& other);
 ```
@@ -191,6 +192,7 @@ void swap(flat_set& other);
 
 ```cpp
 size_type count(const key_type& key) const;
+template < typename K > size_type count(const K& key) const;
 
 iterator find(const key_type& key);
 const_iterator find(const key_type& key) const;
@@ -201,6 +203,9 @@ template < typename K > const_iterator find(const K& key) const;
 std::pair<iterator, iterator> equal_range(const key_type& key);
 std::pair<const_iterator, const_iterator> equal_range(const key_type& key) const;
 
+template < typename K > std::pair<iterator, iterator> equal_range(const K& key);
+template < typename K > std::pair<const_iterator, const_iterator> equal_range(const K& key) const;
+
 iterator lower_bound(const key_type& key);
 const_iterator lower_bound(const key_type& key) const;
 
@@ -399,6 +404,9 @@ mapped_type& operator[](const key_type& key);
 
 mapped_type& at(const key_type& key);
 const mapped_type& at(const key_type& key) const;
+
+template < typename K > mapped_type& at(const K& key);
+template < typename K > const mapped_type& at(const K& key) const;
 ```
 
 ### Modifiers
@@ -423,6 +431,7 @@ void clear();
 iterator erase(const_iterator iter);
 iterator erase(const_iterator first, const_iterator last);
 size_type erase(const key_type& key);
+template < typename K > size_type erase(const K& key);
 
 void swap(flat_map& other)
 ```
@@ -431,6 +440,7 @@ void swap(flat_map& other)
 
 ```cpp
 size_type count(const key_type& key) const;
+template < typename K > size_type count(const K& key) const;
 
 iterator find(const key_type& key);
 const_iterator find(const key_type& key) const;
@@ -441,6 +451,9 @@ template < typename K > const_iterator find(const K& key) const;
 std::pair<iterator, iterator> equal_range(const key_type& key);
 std::pair<const_iterator, const_iterator> equal_range(const key_type& key) const;
 
+template < typename K > std::pair<iterator, iterator> equal_range(const K& key);
+template < typename K > std::pair<const_iterator, const_iterator> equal_range(const K& key) const;
+
 iterator lower_bound(const key_type& key);
 const_iterator lower_bound(const key_type& key) const;
 
@@ -653,6 +666,7 @@ void clear();
 iterator erase(const_iterator iter);
 iterator erase(const_iterator first, const_iterator last);
 size_type erase(const key_type& key);
+template < typename K > size_type erase(const K& key);
 
 void swap(flat_multiset& other);
 ```
@@ -661,6 +675,7 @@ void swap(flat_multiset& other);
 
 ```cpp
 size_type count(const key_type& key) const;
+template < typename K > size_type count(const K& key) const;
 
 iterator find(const key_type& key);
 const_iterator find(const key_type& key) const;
@@ -671,6 +686,9 @@ template < typename K > const_iterator find(const K& key) const;
 std::pair<iterator, iterator> equal_range(const key_type& key);
 std::pair<const_iterator, const_iterator> equal_range(const key_type& key) const;
 
+template < typename K > std::pair<iterator, iterator> equal_range(const K& key);
+template < typename K > std::pair<const_iterator, const_iterator> equal_range(const K& key) const;
+
 iterator lower_bound(const key_type& key);
 const_iterator lower_bound(const key_type& key) const;
 
@@ -869,6 +887,9 @@ mapped_type& operator[](const key_type& key);
 
 mapped_type& at(const key_type& key);
 const mapped_type& at(const key_type& key) const;
+
+template < typename K > mapped_type& at(const K& key);
+template < typename K > const mapped_type& at(const K& key) const;
 ```
 
 ### Modifiers
@@ -893,6 +914,7 @@ void clear();
 iterator erase(const_iterator iter);
 iterator erase(const_iterator first, const_iterator last);
 size_type erase(const key_type& key);
+template < typename K > size_type erase(const K& key);
 
 void swap(flat_multimap& other)
 ```
@@ -901,6 +923,7 @@ void swap(flat_multimap& other)
 
 ```cpp
 size_type count(const key_type& key) const;
+template < typename K > size_type count(const K& key) const;
 
 iterator find(const key_type& key);
 const_iterator find(const key_type& key) const;
@@ -911,6 +934,9 @@ template < typename K > const_iterator find(const K& key) const;
 std::pair<iterator, iterator> equal_range(const key_type& key);
 std::pair<const_iterator, const_iterator> equal_range(const key_type& key) const;
 
+template < typename K > std::pair<iterator, iterator> equal_range(const K& key);
+template < typename K > std::pair<const_iterator, const_iterator> equal_range(const K& key) const;
+
 iterator lower_bound(const key_type& key);
 const_iterator lower_bound(const key_type& key) const;