diff --git a/input_colors_internal.h b/input_colors_internal.h
new file mode 100644
index 0000000..1f1dec6
--- /dev/null
+++ b/input_colors_internal.h
@@ -0,0 +1,8 @@
+#ifndef INPUT_COLORS_INTERNAL_H_INCLUDED
+#define INPUT_COLORS_INTERNAL_H_INCLUDED
+
+void
+ input_colors(std::string &colors_stroke, std::string &colors_fill);
+
+
+#endif // INPUT_COLORS_INTERNAL_H_INCLUDED