diff --git a/docs/reference/swe-glib/swe-glib-sections.txt b/docs/reference/swe-glib/swe-glib-sections.txt
index ad5e78a..a0b2849 100644
--- a/docs/reference/swe-glib/swe-glib-sections.txt
+++ b/docs/reference/swe-glib/swe-glib-sections.txt
@@ -42,9 +42,10 @@ gswe_moment_get_type
 
 <SECTION>
 <FILE>gswe-moon-phase-data</FILE>
-gswe_moon_phase_data_set_phase
+gswe_moon_phase_data_new
+gswe_moon_phase_data_ref
+gswe_moon_phase_data_unref
 gswe_moon_phase_data_get_phase
-gswe_moon_phase_data_set_illumination
 gswe_moon_phase_data_get_illumination
 GsweMoonPhaseData
 <SUBSECTION Standard>
diff --git a/src/gswe-moment.c b/src/gswe-moment.c
index 5a5fe00..20929a7 100644
--- a/src/gswe-moment.c
+++ b/src/gswe-moment.c
@@ -75,7 +75,7 @@ struct _GsweMomentPrivate {
     GHashTable *element_points;
     GHashTable *quality_points;
     guint moon_phase_revision;
-    GsweMoonPhaseData moon_phase;
+    GsweMoonPhaseData *moon_phase;
     GList *aspect_list;
     guint aspect_revision;
     GList *antiscia_list;
@@ -166,6 +166,7 @@ gswe_moment_init(GsweMoment *moment)
     moment->priv->planet_list = NULL;
     moment->priv->aspect_list = NULL;
     moment->priv->antiscia_list = NULL;
+    moment->priv->moon_phase = gswe_moon_phase_data_new();
     moment->priv->element_points = g_hash_table_new_full(g_direct_hash, g_direct_equal, NULL, NULL);
     moment->priv->quality_points = g_hash_table_new_full(g_direct_hash, g_direct_equal, NULL, NULL);
     moment->priv->house_revision = 0;
@@ -203,6 +204,7 @@ gswe_moment_finalize(GObject *gobject)
     g_list_free_full(moment->priv->house_list, g_free);
     g_list_free_full(moment->priv->planet_list, (GDestroyNotify)gswe_planet_data_unref);
     g_list_free_full(moment->priv->aspect_list, (GDestroyNotify)gswe_aspect_data_unref);
+    gswe_moon_phase_data_unref(moment->priv->moon_phase);
 
     G_OBJECT_CLASS(gswe_moment_parent_class)->finalize(gobject);
 }
@@ -964,7 +966,7 @@ gswe_moment_get_moon_phase(GsweMoment *moment, GError **err)
             jdb;
 
     if (moment->priv->moon_phase_revision == moment->priv->revision) {
-        return &(moment->priv->moon_phase);
+        return moment->priv->moon_phase;
     }
 
     jd = gswe_timestamp_get_julian_day(moment->priv->timestamp, err);
@@ -990,31 +992,31 @@ gswe_moment_get_moon_phase(GsweMoment *moment, GError **err)
         g_error("Error during Moon phase calculation!");
     }
 
-    moment->priv->moon_phase.illumination = (50.0 - fabs(phase_percent - 50.0)) * 2;
+    moment->priv->moon_phase->illumination = (50.0 - fabs(phase_percent - 50.0)) * 2;
 
     if (phase_percent == 0) {
-        moment->priv->moon_phase.phase = GSWE_MOON_PHASE_NEW;
+        moment->priv->moon_phase->phase = GSWE_MOON_PHASE_NEW;
     } else if (phase_percent < 25) {
-        moment->priv->moon_phase.phase = GSWE_MOON_PHASE_WAXING_CRESCENT;
+        moment->priv->moon_phase->phase = GSWE_MOON_PHASE_WAXING_CRESCENT;
     } else if (phase_percent == 25) {
-        moment->priv->moon_phase.phase = GSWE_MOON_PHASE_WAXING_HALF;
+        moment->priv->moon_phase->phase = GSWE_MOON_PHASE_WAXING_HALF;
     } else if (phase_percent < 50) {
-        moment->priv->moon_phase.phase = GSWE_MOON_PHASE_WAXING_GIBBOUS;
+        moment->priv->moon_phase->phase = GSWE_MOON_PHASE_WAXING_GIBBOUS;
     } else if (phase_percent == 50) {
-        moment->priv->moon_phase.phase = GSWE_MOON_PHASE_FULL;
+        moment->priv->moon_phase->phase = GSWE_MOON_PHASE_FULL;
     } else if (phase_percent < 75) {
-        moment->priv->moon_phase.phase = GSWE_MOON_PHASE_WANING_GIBBOUS;
+        moment->priv->moon_phase->phase = GSWE_MOON_PHASE_WANING_GIBBOUS;
     } else if (phase_percent == 75) {
-        moment->priv->moon_phase.phase = GSWE_MOON_PHASE_WANING_HALF;
+        moment->priv->moon_phase->phase = GSWE_MOON_PHASE_WANING_HALF;
     } else if (phase_percent < 100) {
-        moment->priv->moon_phase.phase = GSWE_MOON_PHASE_WANING_CRESCENT;
+        moment->priv->moon_phase->phase = GSWE_MOON_PHASE_WANING_CRESCENT;
     } else {
-        moment->priv->moon_phase.phase = GSWE_MOON_PHASE_DARK;
+        moment->priv->moon_phase->phase = GSWE_MOON_PHASE_DARK;
     }
 
     moment->priv->moon_phase_revision = moment->priv->revision;
 
-    return &(moment->priv->moon_phase);
+    return moment->priv->moon_phase;
 }
 
 static gint
diff --git a/src/gswe-moon-phase-data-private.h b/src/gswe-moon-phase-data-private.h
index e60acf7..afb4833 100644
--- a/src/gswe-moon-phase-data-private.h
+++ b/src/gswe-moon-phase-data-private.h
@@ -28,9 +28,10 @@ struct _GsweMoonPhaseData {
 
     /* the illumination percentage of the Moon */
     gdouble illumination;
-};
 
-GsweMoonPhaseData *gswe_moon_phase_data_copy(GsweMoonPhaseData *moon_phase_data);
+    /* reference count */
+    guint refcount;
+};
 
 #endif /* __SWE_GLIB_GSWE_MOON_PHASE_DATA_PRIVATE_H__ */
 #else /* not defined __SWE_GLIB_BUILDING__ */
diff --git a/src/gswe-moon-phase-data.c b/src/gswe-moon-phase-data.c
index ff6ace8..dc4975e 100644
--- a/src/gswe-moon-phase-data.c
+++ b/src/gswe-moon-phase-data.c
@@ -32,37 +32,59 @@
  * Moon, including its illumination percentage.
  */
 
-G_DEFINE_BOXED_TYPE(GsweMoonPhaseData, gswe_moon_phase_data, (GBoxedCopyFunc)gswe_moon_phase_data_copy, (GBoxedFreeFunc)g_free);
+G_DEFINE_BOXED_TYPE(GsweMoonPhaseData, gswe_moon_phase_data, (GBoxedCopyFunc)gswe_moon_phase_data_ref, (GBoxedFreeFunc)gswe_moon_phase_data_unref);
 
+/**
+ * gswe_moon_phase_data_new:
+ *
+ * Creates a new #GsweMoonPhaseData object with reference count set to 1.
+ *
+ * Returns: (transfer full): a new #GsweMoonPhaseData object
+ */
 GsweMoonPhaseData *
-gswe_moon_phase_data_copy(GsweMoonPhaseData *moon_phase_data)
+gswe_moon_phase_data_new(void)
 {
-    GsweMoonPhaseData *ret = g_new0(struct _GsweMoonPhaseData, 1);
+    GsweMoonPhaseData *ret;
 
-    ret->phase = moon_phase_data->phase;
-    ret->illumination = moon_phase_data->illumination;
+    ret = g_new0(GsweMoonPhaseData, 1);
+    ret->refcount = 1;
 
     return ret;
 }
 
 /**
- * gswe_moon_phase_data_set_phase:
- * @moon_phase_data: a GsweMoonPhaseData
- * @phase: the phase to set
+ * gswe_moon_phase_data_ref:
+ * @moon_phase_data: (in): a #GsweMoonPhaseData
  *
- * Sets the phase of the Moon in the given GsweMoonPhaseData.
+ * Increases reference count on @moon_phase_data by one.
+ *
+ * Returns: (transfer none): the same #GsweMoonPhaseData
+ */
+GsweMoonPhaseData *
+gswe_moon_phase_data_ref(GsweMoonPhaseData *moon_phase_data)
+{
+    moon_phase_data->refcount++;
+
+    return moon_phase_data;
+}
+
+/**
+ * gswe_moon_phase_data_unref:
+ * @moon_phase_data: (in): a #GsweMoonPhaseData
+ *
+ * Decreases reference count on @moon_phase_data by one. If reference count drops to zero, @moon_phase_data is freed.
  */
 void
-gswe_moon_phase_data_set_phase(GsweMoonPhaseData *moon_phase_data, GsweMoonPhase phase)
+gswe_moon_phase_data_unref(GsweMoonPhaseData *moon_phase_data)
 {
-    if (moon_phase_data) {
-        moon_phase_data->phase = phase;
+    if (--moon_phase_data->refcount == 0) {
+        g_free(moon_phase_data);
     }
 }
 
 /**
  * gswe_moon_phase_data_get_phase:
- * @moon_phase_data: a GsweMoonPhaseData
+ * @moon_phase_data: (in): a GsweMoonPhaseData
  *
  * Gets the phase of the Moon in the given GsweMoonPhaseData.
  *
@@ -78,24 +100,9 @@ gswe_moon_phase_data_get_phase(GsweMoonPhaseData *moon_phase_data)
     }
 }
 
-/**
- * gswe_moon_phase_data_set_illumination:
- * @moon_phase_data: a GsweMoonPhaseData
- * @illumination: the illumination to set
- *
- * Sets the illumination percentage in the given GsweMoonPhaseData.
- */
-void
-gswe_moon_phase_data_set_illumination(GsweMoonPhaseData *moon_phase_data, gdouble illumination)
-{
-    if (moon_phase_data) {
-        moon_phase_data->illumination = illumination;
-    }
-}
-
 /**
  * gswe_moon_phase_data_get_illumination:
- * @moon_phase_data: a GsweMoonPhaseData
+ * @moon_phase_data: (in): a GsweMoonPhaseData
  *
  * Gets the illumination percentage from the given GsweMoonPhaseData.
  *
diff --git a/src/gswe-moon-phase-data.h b/src/gswe-moon-phase-data.h
index ddff08b..22ef372 100644
--- a/src/gswe-moon-phase-data.h
+++ b/src/gswe-moon-phase-data.h
@@ -34,9 +34,12 @@ G_BEGIN_DECLS
  */
 typedef struct _GsweMoonPhaseData GsweMoonPhaseData;
 
-void gswe_moon_phase_data_set_phase(GsweMoonPhaseData *moon_phase_data, GsweMoonPhase phase);
+GsweMoonPhaseData *gswe_moon_phase_data_new(void);
+
+GsweMoonPhaseData *gswe_moon_phase_data_ref(GsweMoonPhaseData *moon_phase_data);
+void gswe_moon_phase_data_unref(GsweMoonPhaseData *moon_phase_data);
+
 GsweMoonPhase gswe_moon_phase_data_get_phase(GsweMoonPhaseData *moon_phase_data);
-void gswe_moon_phase_data_set_illumination(GsweMoonPhaseData *moon_phase_data, gdouble illumination);
 gdouble gswe_moon_phase_data_get_illumination(GsweMoonPhaseData *moon_phase_data);
 
 GType gswe_moon_phase_data_get_type(void);