diff --git a/include/fmt/core.h b/include/fmt/core.h
index 7a654e2b86d2..2625d86bf37b 100644
--- a/include/fmt/core.h
+++ b/include/fmt/core.h
@@ -73,7 +73,8 @@
 # endif
 #endif
 
-#if FMT_HAS_FEATURE(cxx_explicit_conversions)
+#if FMT_HAS_FEATURE(cxx_explicit_conversions) || \
+    FMT_MSC_VER >= 1800
 # define FMT_EXPLICIT explicit
 #else
 # define FMT_EXPLICIT
@@ -970,8 +971,17 @@ class format_arg_store {
 
   friend class basic_format_args<Context>;
 
+  static FMT_CONSTEXPR uint64_t get_types() {
+    return IS_PACKED ? internal::get_types<Context, Args...>()
+                : -static_cast<int64_t>(NUM_ARGS);
+  }
+
  public:
+#if FMT_USE_CONSTEXPR
+  static constexpr uint64_t TYPES = get_types();
+#else
   static const uint64_t TYPES;
+#endif
 
 #if FMT_GCC_VERSION && FMT_GCC_VERSION <= 405
   // Workaround an array initialization bug in gcc 4.5 and earlier.
@@ -984,10 +994,10 @@ class format_arg_store {
 #endif
 };
 
+#if !FMT_USE_CONSTEXPR
 template <typename Context, typename ...Args>
-const uint64_t format_arg_store<Context, Args...>::TYPES = IS_PACKED ?
-    internal::get_types<Context, Args...>() :
-    -static_cast<int64_t>(NUM_ARGS);
+const uint64_t format_arg_store<Context, Args...>::TYPES = get_types();
+#endif
 
 /**
   \rst
diff --git a/include/fmt/format.h b/include/fmt/format.h
index e9c16b1f3105..3d35a18c5627 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -1381,13 +1381,13 @@ class float_type_checker : private ErrorHandler {
   }
 };
 
-template <typename ErrorHandler>
+template <typename ErrorHandler, typename CharType>
 class char_specs_checker : public ErrorHandler {
  private:
-  char type_;
+  CharType type_;
 
  public:
-  FMT_CONSTEXPR char_specs_checker(char type, ErrorHandler eh)
+  FMT_CONSTEXPR char_specs_checker(CharType type, ErrorHandler eh)
     : ErrorHandler(eh), type_(type) {}
 
   FMT_CONSTEXPR void on_int() {
@@ -3110,8 +3110,10 @@ struct formatter<
             type_spec, internal::int_type_checker<decltype(eh)>(eh));
       break;
     case internal::char_type:
-      handle_char_specs(specs_, internal::char_specs_checker<decltype(eh)>(
-                          type_spec, eh));
+      handle_char_specs(
+          specs_,
+          internal::char_specs_checker<decltype(eh), decltype(type_spec)>(
+              type_spec, eh));
       break;
     case internal::double_type:
     case internal::long_double_type: