diff --git a/libgimpcolor/gimpcolor.def b/libgimpcolor/gimpcolor.def
index d7697ed517..9ba1293568 100644
--- a/libgimpcolor/gimpcolor.def
+++ b/libgimpcolor/gimpcolor.def
@@ -26,6 +26,7 @@ EXPORTS
 	gimp_color_managed_profile_changed
 	gimp_hsl_get_type
 	gimp_hsl_set
+	gimp_hsl_set_alpha
 	gimp_hsl_to_rgb
 	gimp_hsl_to_rgb_int
 	gimp_hsv_clamp