diff --git a/bench/bm_pmt_dict_pack_unpack.cpp b/bench/bm_pmt_dict_pack_unpack.cpp
index 670ddb0..6eba198 100644
--- a/bench/bm_pmt_dict_pack_unpack.cpp
+++ b/bench/bm_pmt_dict_pack_unpack.cpp
@@ -7,6 +7,7 @@
 #include "CLI/Formatter.hpp"
 
 #include <pmtv/pmt.hpp>
+#include <pmtv/format.hpp>
 
 using namespace pmtv;
 
diff --git a/bench/bm_pmt_dict_ref.cpp b/bench/bm_pmt_dict_ref.cpp
index f30f534..6f057c8 100644
--- a/bench/bm_pmt_dict_ref.cpp
+++ b/bench/bm_pmt_dict_ref.cpp
@@ -7,6 +7,7 @@
 #include "CLI/Formatter.hpp"
 
 #include <pmtv/pmt.hpp>
+#include <pmtv/format.hpp>
 
 using namespace pmtv;
 
diff --git a/include/pmtv/format.hpp b/include/pmtv/format.hpp
new file mode 100644
index 0000000..feba6f4
--- /dev/null
+++ b/include/pmtv/format.hpp
@@ -0,0 +1,120 @@
+// Support for std::format is really spotty.
+// Gcc12 does not support it.
+// Eventually replace with std::format when that is widely available.
+#include <fmt/format.h>
+
+namespace fmt {
+template <>
+struct formatter<pmtv::map_t::value_type> {
+    template <typename ParseContext>
+    constexpr auto parse(ParseContext& ctx) {
+        return ctx.begin();
+    }
+
+    template <typename FormatContext>
+    auto format(const pmtv::map_t::value_type& kv, FormatContext& ctx) const {
+        return fmt::format_to(ctx.out(), "{}: {}", kv.first, kv.second);
+    }
+};
+
+template <pmtv::Complex C>
+struct formatter<C> {
+    template <typename ParseContext>
+    constexpr auto parse(ParseContext& ctx) {
+        return ctx.begin();
+    }
+
+    template <typename FormatContext>
+    auto format(const C& arg, FormatContext& ctx) const {
+        if (arg.imag() >= 0)
+            return fmt::format_to(ctx.out(), "{0}+j{1}", arg.real(), arg.imag());
+        else
+            return fmt::format_to(ctx.out(), "{0}-j{1}", arg.real(), -arg.imag());
+    }
+};
+
+
+template<pmtv::IsPmt P>
+struct formatter<P>
+{
+
+    template <typename ParseContext>
+    constexpr auto parse(ParseContext& ctx) {
+        return ctx.begin();
+    }
+
+    template <typename FormatContext>
+    auto format(const P& value, FormatContext& ctx) const {
+        // Due to an issue with the c++ spec that has since been resolved, we have to do something
+        // funky here.  See
+        // https://stackoverflow.com/questions/37526366/nested-constexpr-function-calls-before-definition-in-a-constant-expression-con
+        // This problem only appears to occur in gcc 11 in certain optimization modes. The problem
+        // occurs when we want to format a vector<pmt>.  Ideally, we can write something like:
+        //      return fmt::format_to(ctx.out(), "[{}]", fmt::join(arg, ", "));
+        // It looks like the issue effects clang 14/15 as well.
+        // However, due to the above issue, it fails to compile.  So we have to do the equivalent
+        // ourselves.  We can't recursively call the formatter, but we can recursively call a lambda
+        // function that does the formatting.
+        // It gets more complicated, because we need to pass the function into the lambda.  We can't
+        // pass in the lamdba as it is defined, so we create a nested lambda.  Which accepts a function
+        // as a argument.
+        // Because we are calling std::visit, we can't pass non-variant arguments to the visitor, so we
+        // have to create a new nested lambda every time we format a vector to ensure that it works.
+        using namespace pmtv;
+        using ret_type = decltype(fmt::format_to(ctx.out(), ""));
+        auto format_func = [&ctx](const auto format_arg) {
+            auto function_main = [&ctx](const auto arg, auto function) -> ret_type {
+            using namespace pmtv;
+            using T = std::decay_t<decltype(arg)>;
+            if constexpr (Scalar<T> || Complex<T>)
+                return fmt::format_to(ctx.out(), "{}", arg);
+            else if constexpr (std::same_as<T, std::string>)
+                return fmt::format_to(ctx.out(), "{}",  arg);
+            else if constexpr (UniformVector<T> || UniformStringVector<T>)
+                return fmt::format_to(ctx.out(), "[{}]", fmt::join(arg, ", "));
+            else if constexpr (std::same_as<T, std::vector<pmt>>) {
+                fmt::format_to(ctx.out(), "[");
+                auto new_func = [&function](const auto new_arg) -> ret_type { return function(new_arg, function); };
+                for (auto& a: std::span(arg).first(arg.size()-1)) {
+                    std::visit(new_func, a);
+                    fmt::format_to(ctx.out(), ", ");
+                }
+                std::visit(new_func, arg[arg.size()-1]);
+                return fmt::format_to(ctx.out(), "]");
+                // When we drop support for gcc11/clang15, get rid of the nested lambda and replace
+                // the above with this line.
+                //return fmt::format_to(ctx.out(), "[{}]", fmt::join(arg, ", "));
+            } else if constexpr (PmtMap<T>) {
+                fmt::format_to(ctx.out(), "{{");
+                auto new_func = [&function](const auto new_arg) -> ret_type { return function(new_arg, function); };
+                size_t i = 0;
+                for (auto& [k, v]: arg) {
+                    fmt::format_to(ctx.out(), "{}: ", k);
+                    std::visit(new_func, v);
+                    if (i++ < arg.size() - 1)
+                        fmt::format_to(ctx.out(), ", ");
+                }
+                return fmt::format_to(ctx.out(), "}}");
+                // When we drop support for gcc11/clang15, get rid of the nested lambda and replace
+                // the above with this line.
+                //return fmt::format_to(ctx.out(), "{{{}}}", fmt::join(arg, ", "));
+            } else if constexpr (std::same_as<std::monostate, T>)
+                return fmt::format_to(ctx.out(), "null");
+            return fmt::format_to(ctx.out(), "unknown type {}", typeid(T).name());
+            };
+            return function_main(format_arg, function_main);
+        };
+        return std::visit(format_func, value);
+
+    }
+};
+
+} // namespace fmt
+
+namespace pmtv {
+    template <IsPmt P>
+    std::ostream& operator<<(std::ostream& os, const P& value) {
+        os << fmt::format("{}", value);
+        return os;
+    }
+}
diff --git a/include/pmtv/meson.build b/include/pmtv/meson.build
index 9edb38e..f67cc41 100644
--- a/include/pmtv/meson.build
+++ b/include/pmtv/meson.build
@@ -1,4 +1,5 @@
 files = [
+    'format.hpp',
     'pmt.hpp',
     'rva_variant.hpp',
     'type_helpers.hpp',
diff --git a/include/pmtv/pmt.hpp b/include/pmtv/pmt.hpp
index 73ce0c6..9326a95 100644
--- a/include/pmtv/pmt.hpp
+++ b/include/pmtv/pmt.hpp
@@ -21,11 +21,6 @@
 #pragma GCC diagnostic pop
 #endif
 
-// Support for std::format is really spotty.
-// Gcc12 does not support it.
-// Eventually replace with std::format when that is widely available.
-#include <fmt/format.h>
-
 namespace pmtv {
 
 using pmt = pmt_var_t;
@@ -528,7 +523,7 @@ T cast(const P& value)
     return std::visit(
         [](const auto& arg) -> T {
             using U = std::decay_t<decltype(arg)>;
-            if constexpr (std::constructible_from<T, U>) {
+            if constexpr (std::convertible_to<U, T> || (Complex<T> && Complex<U>)) {
                 if constexpr(Complex<T>) {
                     if constexpr (std::integral<U> || std::floating_point<U>) {
                         return std::complex<typename T::value_type>(static_cast<typename T::value_type>(arg));
@@ -543,127 +538,9 @@ T cast(const P& value)
             //     return std::get<std::map<std::string, pmt_var_t, std::less<>>>(arg);
             // }
             else
-                throw std::runtime_error(fmt::format(
-                    "Invalid PMT Cast {} {}", typeid(T).name(), typeid(U).name()));
+                throw std::runtime_error("Invalid PMT Cast " + std::string(typeid(T).name()) + " " + std::string(typeid(U).name()));
         },
         value);
 }
 
 } // namespace pmtv
-
-namespace fmt {
-template <>
-struct formatter<pmtv::map_t::value_type> {
-    template <typename ParseContext>
-    constexpr auto parse(ParseContext& ctx) {
-        return ctx.begin();
-    }
-
-    template <typename FormatContext>
-    auto format(const pmtv::map_t::value_type& kv, FormatContext& ctx) const {
-        return fmt::format_to(ctx.out(), "{}: {}", kv.first, kv.second);
-    }
-};
-
-template <pmtv::Complex C>
-struct formatter<C> {
-    template <typename ParseContext>
-    constexpr auto parse(ParseContext& ctx) {
-        return ctx.begin();
-    }
-
-    template <typename FormatContext>
-    auto format(const C& arg, FormatContext& ctx) const {
-        if (arg.imag() >= 0)
-            return fmt::format_to(ctx.out(), "{0}+j{1}", arg.real(), arg.imag());
-        else
-            return fmt::format_to(ctx.out(), "{0}-j{1}", arg.real(), -arg.imag());
-    }
-};
-
-
-template<pmtv::IsPmt P>
-struct formatter<P>
-{
-
-    template <typename ParseContext>
-    constexpr auto parse(ParseContext& ctx) {
-        return ctx.begin();
-    }
-
-    template <typename FormatContext>
-    auto format(const P& value, FormatContext& ctx) const {
-        // Due to an issue with the c++ spec that has since been resolved, we have to do something
-        // funky here.  See
-        // https://stackoverflow.com/questions/37526366/nested-constexpr-function-calls-before-definition-in-a-constant-expression-con
-        // This problem only appears to occur in gcc 11 in certain optimization modes. The problem
-        // occurs when we want to format a vector<pmt>.  Ideally, we can write something like:
-        //      return fmt::format_to(ctx.out(), "[{}]", fmt::join(arg, ", "));
-        // It looks like the issue effects clang 14/15 as well.
-        // However, due to the above issue, it fails to compile.  So we have to do the equivalent
-        // ourselves.  We can't recursively call the formatter, but we can recursively call a lambda
-        // function that does the formatting.
-        // It gets more complicated, because we need to pass the function into the lambda.  We can't
-        // pass in the lamdba as it is defined, so we create a nested lambda.  Which accepts a function
-        // as a argument.
-        // Because we are calling std::visit, we can't pass non-variant arguments to the visitor, so we
-        // have to create a new nested lambda every time we format a vector to ensure that it works.
-        using namespace pmtv;
-        using ret_type = decltype(fmt::format_to(ctx.out(), ""));
-        auto format_func = [&ctx](const auto format_arg) {
-            auto function_main = [&ctx](const auto arg, auto function) -> ret_type {
-            using namespace pmtv;
-            using T = std::decay_t<decltype(arg)>;
-            if constexpr (Scalar<T> || Complex<T>)
-                return fmt::format_to(ctx.out(), "{}", arg);
-            else if constexpr (std::same_as<T, std::string>)
-                return fmt::format_to(ctx.out(), "{}",  arg);
-            else if constexpr (UniformVector<T> || UniformStringVector<T>)
-                return fmt::format_to(ctx.out(), "[{}]", fmt::join(arg, ", "));
-            else if constexpr (std::same_as<T, std::vector<pmt>>) {
-                fmt::format_to(ctx.out(), "[");
-                auto new_func = [&function](const auto new_arg) -> ret_type { return function(new_arg, function); };
-                for (auto& a: std::span(arg).first(arg.size()-1)) {
-                    std::visit(new_func, a);
-                    fmt::format_to(ctx.out(), ", ");
-                }
-                std::visit(new_func, arg[arg.size()-1]);
-                return fmt::format_to(ctx.out(), "]");
-                // When we drop support for gcc11/clang15, get rid of the nested lambda and replace
-                // the above with this line.
-                //return fmt::format_to(ctx.out(), "[{}]", fmt::join(arg, ", "));
-            } else if constexpr (PmtMap<T>) {
-                fmt::format_to(ctx.out(), "{{");
-                auto new_func = [&function](const auto new_arg) -> ret_type { return function(new_arg, function); };
-                size_t i = 0;
-                for (auto& [k, v]: arg) {
-                    fmt::format_to(ctx.out(), "{}: ", k);
-                    std::visit(new_func, v);
-                    if (i++ < arg.size() - 1)
-                        fmt::format_to(ctx.out(), ", ");
-                }
-                return fmt::format_to(ctx.out(), "}}");
-                // When we drop support for gcc11/clang15, get rid of the nested lambda and replace
-                // the above with this line.
-                //return fmt::format_to(ctx.out(), "{{{}}}", fmt::join(arg, ", "));
-            } else if constexpr (std::same_as<std::monostate, T>)
-                return fmt::format_to(ctx.out(), "null");
-            return fmt::format_to(ctx.out(), "unknown type {}", typeid(T).name());
-            };
-            return function_main(format_arg, function_main);
-        };
-        return std::visit(format_func, value);
-
-    }
-};
-
-} // namespace fmt
-
-namespace pmtv {
-    template <IsPmt P>
-    std::ostream& operator<<(std::ostream& os, const P& value) {
-        os << fmt::format("{}", value);
-        return os;
-    }
-}
-
diff --git a/python/pmtv/bindings/pmt_python.cc b/python/pmtv/bindings/pmt_python.cc
index d59b24a..7302f8a 100644
--- a/python/pmtv/bindings/pmt_python.cc
+++ b/python/pmtv/bindings/pmt_python.cc
@@ -30,6 +30,7 @@
 namespace py = pybind11;
 
 #include <pmtv/pmt.hpp>
+#include <pmtv/format.hpp>
 
 // pydoc.h is automatically generated in the build directory
 // #include <pmt_pydoc.h>
diff --git a/test/qa_map.cpp b/test/qa_map.cpp
index 6b5c899..80dae56 100644
--- a/test/qa_map.cpp
+++ b/test/qa_map.cpp
@@ -11,6 +11,7 @@
 #include <string_view>
 
 #include <pmtv/pmt.hpp>
+#include <pmtv/format.hpp>
 
 using namespace pmtv;
 
diff --git a/test/qa_scalar.cpp b/test/qa_scalar.cpp
index 8ebbe06..c5d0fdc 100644
--- a/test/qa_scalar.cpp
+++ b/test/qa_scalar.cpp
@@ -10,6 +10,7 @@
 #include <complex>
 
 #include <pmtv/pmt.hpp>
+#include <pmtv/format.hpp>
 #include <sstream>
 
 using namespace pmtv;
diff --git a/test/qa_string.cpp b/test/qa_string.cpp
index abd1298..2225eb6 100644
--- a/test/qa_string.cpp
+++ b/test/qa_string.cpp
@@ -10,6 +10,7 @@
 #include <pmtv/pmt.hpp>
 
 #include <fmt/core.h>
+#include <pmtv/format.hpp>
 #include <string>
 
 using namespace pmtv;
diff --git a/test/qa_uniform_vector.cpp b/test/qa_uniform_vector.cpp
index f79dbff..0a73979 100644
--- a/test/qa_uniform_vector.cpp
+++ b/test/qa_uniform_vector.cpp
@@ -9,6 +9,7 @@
 #include <complex>
 
 #include <pmtv/pmt.hpp>
+#include <pmtv/format.hpp>
 
 #include <list>
 #include <map>
diff --git a/test/qa_vector_of_pmts.cpp b/test/qa_vector_of_pmts.cpp
index 42481de..2efcaf5 100644
--- a/test/qa_vector_of_pmts.cpp
+++ b/test/qa_vector_of_pmts.cpp
@@ -12,6 +12,7 @@
 #include <map>
 
 #include <pmtv/pmt.hpp>
+#include <pmtv/format.hpp>
 
 #include <fmt/core.h>