diff --git a/build.zig b/build.zig
index d4a159e5e6..e886377139 100644
--- a/build.zig
+++ b/build.zig
@@ -16,11 +16,12 @@ pub fn build(b: *Builder) !void {
     var docgen_exe = b.addExecutable("docgen", "doc/docgen.zig");
 
     const rel_zig_exe = try os.path.relative(b.allocator, b.build_root, b.zig_exe);
+    const langref_out_path = os.path.join(b.allocator, b.cache_root, "langref.html") catch unreachable;
     var docgen_cmd = b.addCommand(null, b.env_map, [][]const u8{
         docgen_exe.getOutputPath(),
         rel_zig_exe,
         "doc" ++ os.path.sep_str ++ "langref.html.in",
-        os.path.join(b.allocator, b.cache_root, "langref.html") catch unreachable,
+        langref_out_path,
     });
     docgen_cmd.step.dependOn(&docgen_exe.step);
 
diff --git a/src/main.cpp b/src/main.cpp
index fdc34a83ae..bf6c142975 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -353,7 +353,7 @@ int main(int argc, char **argv) {
     size_t ver_minor = 0;
     size_t ver_patch = 0;
     bool timing_info = false;
-    const char *cache_dir = default_zig_cache_name;
+    const char *cache_dir = nullptr;
     CliPkg *cur_pkg = allocate<CliPkg>(1);
     BuildMode build_mode = BuildModeDebug;
     ZigList<const char *> test_exec_args = {0};
@@ -403,7 +403,7 @@ int main(int argc, char **argv) {
 
         CodeGen *g = codegen_create(build_runner_path, nullptr, OutTypeExe, BuildModeDebug, zig_lib_dir_buf);
         g->enable_time_report = timing_info;
-        buf_init_from_str(&g->cache_dir, cache_dir);
+        buf_init_from_str(&g->cache_dir, cache_dir ? cache_dir : default_zig_cache_name);
         codegen_set_out_name(g, buf_create_from_str("build"));
 
         Buf *build_file_buf = buf_create_from_str(build_file);
@@ -412,8 +412,14 @@ int main(int argc, char **argv) {
         Buf build_file_dirname = BUF_INIT;
         os_path_split(&build_file_abs, &build_file_dirname, &build_file_basename);
 
-        Buf *cache_dir_buf = buf_create_from_str(cache_dir);
-        Buf full_cache_dir = os_path_resolve(&cache_dir_buf, 1);
+
+        Buf full_cache_dir = BUF_INIT;
+        if (cache_dir == nullptr) {
+            os_path_join(&build_file_dirname, buf_create_from_str(default_zig_cache_name), &full_cache_dir);
+        } else {
+            Buf *cache_dir_buf = buf_create_from_str(cache_dir);
+            full_cache_dir = os_path_resolve(&cache_dir_buf, 1);
+        }
 
         args.items[1] = buf_ptr(&build_file_dirname);
         args.items[2] = buf_ptr(&full_cache_dir);
@@ -830,7 +836,7 @@ int main(int argc, char **argv) {
 
             CodeGen *g = codegen_create(zig_root_source_file, target, out_type, build_mode, zig_lib_dir_buf);
             g->enable_time_report = timing_info;
-            buf_init_from_str(&g->cache_dir, cache_dir);
+            buf_init_from_str(&g->cache_dir, cache_dir ? cache_dir : default_zig_cache_name);
             codegen_set_out_name(g, buf_out_name);
             codegen_set_lib_version(g, ver_major, ver_minor, ver_patch);
             codegen_set_is_test(g, cmd == CmdTest);