diff --git a/include/core/set.h b/include/core/set.h
new file mode 100644
index 00000000..5746affa
--- /dev/null
+++ b/include/core/set.h
@@ -0,0 +1,70 @@
+/*
+ * Copyright 2015 (c) Anna Schumaker.
+ */
+#ifndef OCARINA_CORE_SET_H
+#define OCARINA_CORE_SET_H
+
+#include <glib.h>
+#include <stdbool.h>
+
+
+struct set {
+	GHashTable *s_set;
+};
+
+struct set_iter {
+	unsigned int   it_val;
+	GHashTableIter it_iter;
+};
+
+
+#define SET_INIT()								\
+	{									\
+		.s_set = g_hash_table_new(g_direct_hash, g_direct_equal),	\
+	}
+
+
+static inline void set_deinit(struct set *set)
+{
+	g_hash_table_destroy(set->s_set);
+}
+
+static inline void set_insert(struct set *set, unsigned int value)
+{
+	g_hash_table_add(set->s_set, GUINT_TO_POINTER(value));
+}
+
+static inline void set_remove(struct set *set, unsigned int value)
+{
+	g_hash_table_remove(set->s_set, GUINT_TO_POINTER(value));
+}
+
+static inline bool set_has(const struct set *set, unsigned int value)
+{
+	return g_hash_table_contains(set->s_set, GUINT_TO_POINTER(value));
+}
+
+static inline unsigned int set_size(struct set *set)
+{
+	return g_hash_table_size(set->s_set);
+}
+
+
+
+static inline bool set_iter_next(struct set_iter *it)
+{
+	gpointer key;
+	bool ret    = g_hash_table_iter_next(&it->it_iter, &key, NULL);
+	it->it_val  = GPOINTER_TO_INT(key);
+	return ret;
+}
+
+static inline void set_iter_init(const struct set *set, struct set_iter *it)
+{
+	g_hash_table_iter_init(&it->it_iter, set->s_set);
+}
+
+#define set_for_each(set, it) \
+	for (set_iter_init(set, it); set_iter_next(it); )
+
+#endif /* OCARINA_CORE_SET_H */
diff --git a/tests/core/.gitignore b/tests/core/.gitignore
index 42a64a8f..06c07df3 100644
--- a/tests/core/.gitignore
+++ b/tests/core/.gitignore
@@ -1,15 +1,16 @@
-version
-string
-file
-date
+audio
 database
-index
-filter
-idle
-random
-queue
-library
-playlist
+date
 deck
 driver
-audio
+file
+filter
+idle
+index
+library
+playlist
+queue
+random
+set
+string
+version
diff --git a/tests/core/Sconscript b/tests/core/Sconscript
index 3556bbed..ca2045d6 100644
--- a/tests/core/Sconscript
+++ b/tests/core/Sconscript
@@ -18,6 +18,7 @@ res += [ CoreTest("string",   "string.c")     ]
 res += [ CoreTest("random",   "random.c")     ]
 res += [ CoreTest("file",     "file.c")       ]
 res += [ CoreTest("date",     "date.c")       ]
+res += [ CoreTest("set",      "set.c")        ]
 res += [ CoreTest("database", "database.cpp") ]
 res += [ CoreTest("index",    "index.cpp")    ]
 res += [ CoreTest("filter",   "filter.cpp")   ]
diff --git a/tests/core/set.c b/tests/core/set.c
new file mode 100644
index 00000000..52d97142
--- /dev/null
+++ b/tests/core/set.c
@@ -0,0 +1,45 @@
+/*
+ * Copyright 2015 (c) Anna Schumaker.
+ */
+#include <core/set.h>
+#include <tests/test.h>
+
+
+void test_set()
+{
+	struct set set = SET_INIT();
+	unsigned int i, N = 10;
+	struct set_iter it;
+
+	/* Insert N items. */
+	for (i = 0; i < N; i++) {
+		set_insert(&set, i);
+		set_insert(&set, i);
+		test_loop_equal(set_size(&set), i + 1, i);
+		test_loop_equal(set_has(&set, i), (bool)true, i);
+	} test_loop_passed();
+
+	set_insert(&set, 0);
+	test_equal(set_size(&set), N);
+
+	/* Remove even items. */
+	for (i = 0; i < N; i += 2) {
+		set_remove(&set, i);
+		set_remove(&set, i);
+		test_loop_equal(set_has(&set, i), (bool)false, i);
+	} test_loop_passed();
+	test_equal(set_size(&set), N / 2);
+
+	/* Test iterating. */
+	i = 1;
+	set_for_each(&set, &it) {
+		test_loop_equal(it.it_val, i, i);
+		i += 2;
+	} test_loop_passed();
+
+	set_deinit(&set);
+}
+
+DECLARE_UNIT_TESTS(
+	UNIT_TEST("Set", test_set),
+);