diff --git a/.gitignore b/.gitignore
index 9491a2f..21dd653 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,6 +3,9 @@
 ##
 ## Get latest from https://github.com/github/gitignore/blob/master/VisualStudio.gitignore
 
+# Project specific
+*.esm
+
 # User-specific files
 *.rsuser
 *.suo
diff --git a/Navmesher/Navmesher.vcxproj b/Navmesher/Navmesher.vcxproj
index d46de5b..08d21a6 100644
--- a/Navmesher/Navmesher.vcxproj
+++ b/Navmesher/Navmesher.vcxproj
@@ -134,6 +134,7 @@
     </Link>
   </ItemDefinitionGroup>
   <ItemGroup>
+    <ClCompile Include="esx_reader.cpp" />
     <ClCompile Include="esx_reader_lut.cpp" />
     <ClCompile Include="main.cpp" />
   </ItemGroup>
diff --git a/Navmesher/Navmesher.vcxproj.filters b/Navmesher/Navmesher.vcxproj.filters
index f460f1b..b8424dd 100644
--- a/Navmesher/Navmesher.vcxproj.filters
+++ b/Navmesher/Navmesher.vcxproj.filters
@@ -21,6 +21,9 @@
     <ClCompile Include="esx_reader_lut.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="esx_reader.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <ClInclude Include="esx_reader.hpp">
diff --git a/Navmesher/esx_reader.cpp b/Navmesher/esx_reader.cpp
new file mode 100644
index 0000000..53a59c6
--- /dev/null
+++ b/Navmesher/esx_reader.cpp
@@ -0,0 +1,4 @@
+#include "esx_reader.hpp"
+
+
+
diff --git a/Navmesher/esx_reader.hpp b/Navmesher/esx_reader.hpp
index 31cf7c4..6cac197 100644
--- a/Navmesher/esx_reader.hpp
+++ b/Navmesher/esx_reader.hpp
@@ -7,6 +7,7 @@
 #include <string_view>
 #include <compare>
 #include <vector>
+#include <type_traits>
 
 #include "utility.hpp"
 
@@ -62,11 +63,13 @@ using Node = std::variant<GroupNode, RecordNode>;
 // Aggregate types
 //
 
+#pragma warning( push )
+#pragma warning( disable : 4514 )
 struct FourCC : utility::Store<uint32_t> {
         constexpr FourCC() noexcept = default;
         explicit constexpr FourCC(const char(&str)[5]) noexcept : Store{ utility::fourcc_lit_to_val(str) } { }
 };
-static_assert(std::is_trivial_v<FourCC>);
+#pragma warning( pop )
 
 struct FormID : utility::Store<uint32_t> { };
 struct Timestamp : utility::Store<uint16_t> { };
@@ -117,7 +120,6 @@ struct GroupHeader {
         VCInfo     version_control_information;
         uint32_t   unknown;
 };
-static_assert(sizeof(GroupHeader) == 24);
 
 struct RecordHeader {
         struct Flags : utility::Store<uint32_t> { };
@@ -132,7 +134,6 @@ struct RecordHeader {
         Version    version;
         uint16_t   unknown;
 };
-static_assert(sizeof(RecordHeader) == 24);
 
 // 
 // Classes
diff --git a/Navmesher/main.cpp b/Navmesher/main.cpp
index 2d6fa4d..771345c 100644
--- a/Navmesher/main.cpp
+++ b/Navmesher/main.cpp
@@ -1,7 +1,33 @@
-#include <iostream>
 #include "esx_reader.hpp"
 
+#include <iostream>
+#include <fstream>
+#include <filesystem>
+
+static constexpr auto esm_name = "Skyrim.esm";
+
+/* Propagated Exceptions:
+ * - std::bad_alloc
+ * - std::filesystem::filesystem_error
+ * - std::ios_base::failure
+ */
+[[nodiscard]] static std::ifstream open_esm(void)
+{
+        std::filesystem::path cwd = std::filesystem::current_path();
+        auto esm_path = cwd / esm_name;
+        auto esm_fs = std::ifstream(esm_path, std::ios::binary);
+        if (esm_fs.fail())
+                throw std::ios_base::failure("Could not open the esm file for reading.");
+        return esm_fs;
+}
+
 int main()
 {
-        std::cout << esxr::flag_to_description({ esxr::RecordType::TES4, 0 }).value() << std::endl;
+        auto esm_fs = open_esm();
+        std::array<char, 4> fourcc{};
+        esm_fs.read(fourcc.data(), static_cast<std::streamsize>(fourcc.size()));
+        for (auto c : fourcc)
+                std::cout << c;
+        std::cout << '\n';
+        return 0;
 }
\ No newline at end of file
diff --git a/Navmesher/utility.hpp b/Navmesher/utility.hpp
index 6dc56cc..bb041d5 100644
--- a/Navmesher/utility.hpp
+++ b/Navmesher/utility.hpp
@@ -15,7 +15,7 @@ struct Store {
         friend constexpr auto operator<=>(const Store &, const Store &) noexcept = default;
 };
 
-// Convert a fourcc literal (e.g. "LITR" to a uint32_t)
+// Convert a fourcc literal (e.g. "LITR") to a uint32_t
 constexpr uint32_t fourcc_lit_to_val(const char(&a)[5]) noexcept
 {
         char temp[4] = { a[0], a[1], a[2], a[3] };
@@ -31,6 +31,7 @@ constexpr std::array<T, N> array_builtin_to_std(const T(&builtin)[N]) noexcept
         return array;
 }
 
+// Convert a std::array of std::pairs to a std::pair of std::arrays
 template <typename First, typename Second, std::size_t N>
 constexpr std::pair<std::array<First, N>, std::array<Second, N>> map_to_soa(std::array<std::pair<First, Second>, N> map) noexcept
 {
@@ -50,7 +51,7 @@ constexpr std::optional<Second> soa_first_to_second(const std::pair<std::array<F
         if (lhs == soa.first.cend())
                 return {};
         auto index = std::distance(soa.first.cbegin(), lhs);
-        return { soa.second[index] };
+        return { soa.second[static_cast<size_t>(index)] };
 }
 
 template <typename First, typename Second, std::size_t N>
@@ -60,7 +61,7 @@ constexpr std::optional<First> soa_second_to_first(const std::pair<std::array<Fi
         if (lhs == soa.second.cend())
                 return {};
         auto index = std::distance(soa.second.cbegin(), lhs);
-        return { soa.first[index] };
+        return { soa.first[static_cast<size_t>(index)] };
 }
 
 // Used to inspect type sizes and values at compile time. Example: