diff --git a/build.zig b/build.zig
index 9c739388..90aab69b 100644
--- a/build.zig
+++ b/build.zig
@@ -38,7 +38,6 @@ pub fn build_exe(
         "reflection.cc",
         "spirv.cc",
         "spirvcross.cc",
-        "util.cc",
         "formats/bare.cc",
         "formats/sokol.cc",
         "formats/sokolnim.cc",
@@ -46,6 +45,7 @@ pub fn build_exe(
         "formats/sokolrust.cc",
         "formats/sokolzig.cc",
         "formats/yaml.cc",
+        "formats/util.cc",
     };
     const incl_dirs = [_][]const u8{
         "src/shdc",
diff --git a/src/shdc/formats/bare.cc b/src/shdc/formats/bare.cc
index 6246480a..976fba01 100644
--- a/src/shdc/formats/bare.cc
+++ b/src/shdc/formats/bare.cc
@@ -52,8 +52,8 @@ static ErrMsg write_shader_sources_and_blobs(const Args& args,
         const BytecodeBlob* fs_blob = find_bytecode_blob_by_shader_name(prog.fs_name, inp, bytecode);
 
         const std::string file_path_base = fmt::format("{}_{}{}_{}", args.output, mod_prefix(inp), prog.name, Slang::to_str(slang));
-        const std::string file_path_vs = fmt::format("{}_vs{}", file_path_base, util::slang_file_extension(slang, vs_blob));
-        const std::string file_path_fs = fmt::format("{}_fs{}", file_path_base, util::slang_file_extension(slang, fs_blob));
+        const std::string file_path_vs = fmt::format("{}_vs{}", file_path_base, util::slang_file_extension(slang, vs_blob != nullptr));
+        const std::string file_path_fs = fmt::format("{}_fs{}", file_path_base, util::slang_file_extension(slang, fs_blob != nullptr));
 
         ErrMsg err;
         err = write_stage(file_path_vs, vs_src, vs_blob);
diff --git a/src/shdc/util.cc b/src/shdc/formats/util.cc
similarity index 99%
rename from src/shdc/util.cc
rename to src/shdc/formats/util.cc
index 3ccaa69b..31f189dd 100644
--- a/src/shdc/util.cc
+++ b/src/shdc/formats/util.cc
@@ -5,7 +5,7 @@
 #include "fmt/format.h"
 #include "pystring.h"
 
-namespace shdc::util {
+namespace shdc::formats::util {
 
 using namespace refl;
 
diff --git a/src/shdc/util.h b/src/shdc/formats/util.h
similarity index 96%
rename from src/shdc/util.h
rename to src/shdc/formats/util.h
index 82816040..309d552b 100644
--- a/src/shdc/util.h
+++ b/src/shdc/formats/util.h
@@ -6,7 +6,7 @@
 #include "types/slang.h"
 #include "types/reflection/uniform.h"
 
-namespace shdc::util {
+namespace shdc::formats::util {
 
 // utility functions for generators
 ErrMsg check_errors(const Input& inp, const Spirvcross& spirvcross, Slang::Enum slang);
diff --git a/src/shdc/formats/yaml.cc b/src/shdc/formats/yaml.cc
index 7b9272fa..ee9aac59 100644
--- a/src/shdc/formats/yaml.cc
+++ b/src/shdc/formats/yaml.cc
@@ -179,8 +179,8 @@ static ErrMsg write_shader_sources_and_blobs(const Args& args,
         const BytecodeBlob* fs_blob = find_bytecode_blob_by_shader_name(prog.fs_name, inp, bytecode);
 
         const std::string file_path_base = fmt::format("{}_{}{}_{}", args.output, mod_prefix(inp), prog.name, Slang::to_str(slang));
-        const std::string file_path_vs = fmt::format("{}_vs{}", file_path_base, util::slang_file_extension(slang, vs_blob));
-        const std::string file_path_fs = fmt::format("{}_fs{}", file_path_base, util::slang_file_extension(slang, fs_blob));
+        const std::string file_path_vs = fmt::format("{}_vs{}", file_path_base, util::slang_file_extension(slang, vs_blob != nullptr));
+        const std::string file_path_fs = fmt::format("{}_fs{}", file_path_base, util::slang_file_extension(slang, fs_blob != nullptr));
 
         L("      -\n");
         L("        name: {}\n", prog.name);