diff --git a/include/ghostty.h b/include/ghostty.h
index e7b6ae716f3..67681e6c8de 100644
--- a/include/ghostty.h
+++ b/include/ghostty.h
@@ -1073,6 +1073,8 @@ GHOSTTY_API void ghostty_config_load_file(ghostty_config_t, const char*);
 GHOSTTY_API void ghostty_config_load_default_files(ghostty_config_t);
 GHOSTTY_API void ghostty_config_load_recursive_files(ghostty_config_t);
 GHOSTTY_API void ghostty_config_finalize(ghostty_config_t);
+GHOSTTY_API void ghostty_config_set_color_scheme(ghostty_config_t,
+                                                    ghostty_color_scheme_e);
 GHOSTTY_API bool ghostty_config_get(ghostty_config_t, void*, const char*, uintptr_t);
 GHOSTTY_API ghostty_input_trigger_s ghostty_config_trigger(ghostty_config_t,
                                                               const char*,
diff --git a/src/config/CApi.zig b/src/config/CApi.zig
index ca15ce4e89f..f72982f3854 100644
--- a/src/config/CApi.zig
+++ b/src/config/CApi.zig
@@ -3,6 +3,7 @@ const inputpkg = @import("../input.zig");
 const state = &@import("../global.zig").state;
 const c = @import("../main_c.zig");
 
+const conditional = @import("conditional.zig");
 const Config = @import("Config.zig");
 const c_get = @import("c_get.zig");
 const edit = @import("edit.zig");
@@ -89,6 +90,24 @@ export fn ghostty_config_finalize(self: *Config) void {
     };
 }
 
+/// Set the color scheme on a configuration's conditional state before
+/// finalization. This ensures that conditional theme resolution (e.g.
+/// `theme = light:Foo,dark:Bar`) uses the correct scheme during
+/// `ghostty_config_finalize`. Must be called before finalize.
+export fn ghostty_config_set_color_scheme(self: *Config, scheme_raw: c_int) void {
+    self._conditional_state.theme = switch (scheme_raw) {
+        0 => .light,
+        1 => .dark,
+        else => {
+            log.warn(
+                "invalid color scheme to ghostty_config_set_color_scheme value={}",
+                .{scheme_raw},
+            );
+            return;
+        },
+    };
+}
+
 export fn ghostty_config_get(
     self: *Config,
     ptr: *anyopaque,