diff --git a/src/library/definitional/eq.cpp b/src/library/definitional/eq.cpp
new file mode 100644
index 000000000..f4dc59802
--- /dev/null
+++ b/src/library/definitional/eq.cpp
@@ -0,0 +1,24 @@
+/*
+Copyright (c) 2014 Microsoft Corporation. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+
+Author: Leonardo de Moura
+*/
+#include "kernel/environment.h"
+
+namespace lean {
+bool has_eq_decls(environment const & env) {
+    auto d = env.find(name({"eq", "refl"}));
+    if (!d)
+        return false;
+    if (length(d->get_univ_params()) != 1)
+        return false;
+    expr type = d->get_type();
+    if (!is_pi(type) || !is_pi(binding_body(type)))
+        return false;
+    type = get_app_fn(binding_body(binding_body(type)));
+    if (!is_constant(type))
+        return false;
+    return const_name(type) == "eq";
+}
+}
diff --git a/src/library/definitional/eq.h b/src/library/definitional/eq.h
new file mode 100644
index 000000000..c1534c47c
--- /dev/null
+++ b/src/library/definitional/eq.h
@@ -0,0 +1,12 @@
+/*
+Copyright (c) 2014 Microsoft Corporation. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+
+Author: Leonardo de Moura
+*/
+#pragma once
+#include "kernel/environment.h"
+
+namespace lean {
+bool has_eq_decls(environment const & env);
+}