diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9d803bac..e7836adb 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -5,7 +5,7 @@ if(POLICY CMP0091)
 endif()
 
 project(prometheus-cpp
-  VERSION 0.12.3
+  VERSION 0.13.0
   DESCRIPTION "Prometheus Client Library for Modern C++"
   HOMEPAGE_URL "https://github.com/jupp0r/prometheus-cpp"
 )
diff --git a/pull/include/prometheus/exposer.h b/pull/include/prometheus/exposer.h
index 85804f04..793225a5 100644
--- a/pull/include/prometheus/exposer.h
+++ b/pull/include/prometheus/exposer.h
@@ -20,19 +20,11 @@ class Endpoint;
 
 class PROMETHEUS_CPP_PULL_EXPORT Exposer {
  public:
-  /// @note This ctor will be merged with the "callback" variant once
-  /// prometheus-cpp 0.13 performs an ABI-break
   explicit Exposer(const std::string& bind_address,
-                   const std::size_t num_threads = 2);
-  /// @note This ctor will be merged with the "callback" variant once
-  /// prometheus-cpp 0.13 performs an ABI-break
-  explicit Exposer(std::vector<std::string> options);
-
-  explicit Exposer(const std::string& bind_address,
-                   const std::size_t num_threads,
-                   const CivetCallbacks* callbacks);
+                   const std::size_t num_threads = 2,
+                   const CivetCallbacks* callbacks = nullptr);
   explicit Exposer(std::vector<std::string> options,
-                   const CivetCallbacks* callbacks);
+                   const CivetCallbacks* callbacks = nullptr);
   ~Exposer();
   void RegisterCollectable(const std::weak_ptr<Collectable>& collectable,
                            const std::string& uri = std::string("/metrics"));
diff --git a/pull/src/exposer.cc b/pull/src/exposer.cc
index f278bbb9..546c9bc1 100644
--- a/pull/src/exposer.cc
+++ b/pull/src/exposer.cc
@@ -11,12 +11,6 @@
 
 namespace prometheus {
 
-Exposer::Exposer(const std::string& bind_address, const std::size_t num_threads)
-    : Exposer(bind_address, num_threads, nullptr) {}
-
-Exposer::Exposer(std::vector<std::string> options)
-    : Exposer(options, nullptr) {}
-
 Exposer::Exposer(const std::string& bind_address, const std::size_t num_threads,
                  const CivetCallbacks* callbacks)
     : Exposer(