diff --git a/tests/color_util.c b/tests/color_util.c
index f51666dd..0e0c738a 100644
--- a/tests/color_util.c
+++ b/tests/color_util.c
@@ -121,6 +121,29 @@ transfer_fn_invert(enum transfer_fn fn)
 	return 0;
 }
 
+const char *
+transfer_fn_name(enum transfer_fn fn)
+{
+	switch (fn) {
+	case TRANSFER_FN_ADOBE_RGB_EOTF:
+		return "AdobeRGB EOTF";
+	case TRANSFER_FN_ADOBE_RGB_EOTF_INVERSE:
+		return "inverse AdobeRGB EOTF";
+	case TRANSFER_FN_IDENTITY:
+		return "identity";
+	case TRANSFER_FN_POWER2_4_EOTF:
+		return "power 2.4";
+	case TRANSFER_FN_POWER2_4_EOTF_INVERSE:
+		return "inverse power 2.4";
+	case TRANSFER_FN_SRGB_EOTF:
+		return "sRGB EOTF";
+	case TRANSFER_FN_SRGB_EOTF_INVERSE:
+		return "inverse sRGB EOTF";
+	}
+	assert(0 && "bad transfer_fn");
+	return 0;
+}
+
 /**
  * NaN comes out as is
  *This function is not intended for hiding NaN.
diff --git a/tests/color_util.h b/tests/color_util.h
index 6b6f96d7..27d7d3c8 100644
--- a/tests/color_util.h
+++ b/tests/color_util.h
@@ -110,6 +110,9 @@ color_float_apply_matrix(const struct lcmsMAT3 *mat, struct color_float c);
 enum transfer_fn
 transfer_fn_invert(enum transfer_fn fn);
 
+const char *
+transfer_fn_name(enum transfer_fn fn);
+
 void
 lcmsMAT3_invert(struct lcmsMAT3 *result, const struct lcmsMAT3 *mat);