diff --git a/src/kernel/metavar.cpp b/src/kernel/metavar.cpp
index b898c5717..1724ba7a5 100644
--- a/src/kernel/metavar.cpp
+++ b/src/kernel/metavar.cpp
@@ -255,6 +255,20 @@ expr substitution::instantiate_metavars_wo_jst(expr const & e, bool inst_local_t
     return instantiate_metavars_fn(*this, false, inst_local_types)(e);
 }
 
+auto substitution::expand_metavar_app(expr const & e) -> opt_expr_jst {
+    expr const & f = get_app_fn(e);
+    if (!is_metavar(f))
+        return opt_expr_jst();
+    name const & f_name = mlocal_name(f);
+    auto f_value = get_expr(f_name);
+    if (!f_value)
+        return opt_expr_jst();
+    buffer<expr> args;
+    get_app_rev_args(e, args);
+    expr new_e = apply_beta(*f_value, args.size(), args.data());
+    return opt_expr_jst(new_e, get_expr_jst(f_name));
+}
+
 static name_set merge(name_set s1, name_set const & s2) {
     s2.for_each([&](name const & n) { s1.insert(n); });
     return s1;
diff --git a/src/kernel/metavar.h b/src/kernel/metavar.h
index 2e73c083c..2be50bef4 100644
--- a/src/kernel/metavar.h
+++ b/src/kernel/metavar.h
@@ -15,6 +15,10 @@ Author: Leonardo de Moura
 
 namespace lean {
 class substitution {
+public:
+    typedef optional<pair<expr,  justification>> opt_expr_jst;
+    typedef optional<pair<level, justification>> opt_level_jst;
+private:
     typedef name_map<expr>                 expr_map;
     typedef name_map<level>                level_map;
     typedef name_map<justification>        jst_map;
@@ -37,19 +41,11 @@ class substitution {
     pair<expr, justification> instantiate_metavars_core(expr const & e, bool inst_local_types);
     bool occurs_expr_core(name const & m, expr const & e, name_set & visited) const;
     name_set get_occs(name const & m, name_set & fresh);
-public:
-    substitution();
-    typedef optional<pair<expr,  justification>> opt_expr_jst;
-    typedef optional<pair<level, justification>> opt_level_jst;
 
-    bool is_expr_assigned(name const & m) const;
     opt_expr_jst get_expr_assignment(name const & m) const;
-
-    bool is_level_assigned(name const & m) const;
+    optional<expr> get_expr(name const & m) const;
     opt_level_jst get_level_assignment(name const & m) const;
 
-    optional<expr> get_expr(name const & m) const;
-    optional<level> get_level(name const & m) const;
     justification get_expr_jst(name const & m) const {
         if (auto it = m_expr_jsts.find(m)) return *it; else return justification();
     }
@@ -57,6 +53,13 @@ public:
         if (auto it = m_level_jsts.find(m)) return *it; else return justification();
     }
 
+public:
+    substitution();
+
+    optional<level> get_level(name const & m) const;
+    bool is_expr_assigned(name const & m) const;
+    bool is_level_assigned(name const & m) const;
+
     void assign(name const & m, expr const & t, justification const & j);
     void assign(name const & m, expr const & t) { assign(m, t, justification()); }
     void assign(expr const & m, expr const & t, justification const & j) { assign(mlocal_name(m), t, j); }
@@ -66,6 +69,9 @@ public:
     void assign(level const & m, level const & t, justification const & j) { assign(meta_id(m), t, j); }
     void assign(level const & m, level const & t) { assign(m, t, justification ()); }
 
+    /** \brief Given e of the form <tt>?m t1 ... t2</tt>, expand ?m and apply beta-reduction */
+    opt_expr_jst expand_metavar_app(expr const & e);
+
     pair<level, justification> instantiate_metavars(level const & l) { return instantiate_metavars(l, true); }
     level instantiate(level const & l) { return instantiate_metavars(l, false).first; }
 
diff --git a/src/library/kernel_bindings.cpp b/src/library/kernel_bindings.cpp
index 620deb9e8..677b3c035 100644
--- a/src/library/kernel_bindings.cpp
+++ b/src/library/kernel_bindings.cpp
@@ -1646,18 +1646,6 @@ static void open_constraint(lua_State * L) {
 // Substitution
 DECL_UDATA(substitution)
 static int mk_substitution(lua_State * L) { return push_substitution(L, substitution()); }
-static int subst_get_expr(lua_State * L) {
-    if (is_expr(L, 2))
-        return push_optional_expr(L, to_substitution(L, 1).get_expr(to_expr(L, 2)));
-    else
-        return push_optional_expr(L, to_substitution(L, 1).get_expr(to_name_ext(L, 2)));
-}
-static int subst_get_level(lua_State * L) {
-    if (is_level(L, 2))
-        return push_optional_level(L, to_substitution(L, 1).get_level(to_level(L, 2)));
-    else
-        return push_optional_level(L, to_substitution(L, 1).get_level(to_name_ext(L, 2)));
-}
 static int subst_assign(lua_State * L) {
     int nargs = lua_gettop(L);
     if (nargs == 3) {
@@ -1697,46 +1685,6 @@ static int subst_is_expr_assigned(lua_State * L) { return push_boolean(L, to_sub
 static int subst_is_level_assigned(lua_State * L) { return push_boolean(L, to_substitution(L, 1).is_level_assigned(to_name_ext(L, 2))); }
 static int subst_occurs(lua_State * L) { return push_boolean(L, to_substitution(L, 1).occurs(to_expr(L, 2), to_expr(L, 3))); }
 static int subst_occurs_expr(lua_State * L) { return push_boolean(L, to_substitution(L, 1).occurs_expr(to_name_ext(L, 2), to_expr(L, 3))); }
-static int subst_get_expr_assignment(lua_State * L) {
-    auto r = to_substitution(L, 1).get_expr_assignment(to_name_ext(L, 2));
-    if (r) {
-        push_expr(L, r->first);
-        push_justification(L, r->second);
-    } else {
-        push_nil(L); push_nil(L);
-    }
-    return 2;
-}
-static int subst_get_level_assignment(lua_State * L) {
-    auto r = to_substitution(L, 1).get_level_assignment(to_name_ext(L, 2));
-    if (r) {
-        push_level(L, r->first);
-        push_justification(L, r->second);
-    } else {
-        push_nil(L); push_nil(L);
-    }
-    return 2;
-}
-static int subst_get_assignment(lua_State * L) {
-    if (is_expr(L, 2)) {
-        auto r = to_substitution(L, 1).get_assignment(to_expr(L, 2));
-        if (r) {
-            push_expr(L, r->first);
-            push_justification(L, r->second);
-        } else {
-            push_nil(L); push_nil(L);
-        }
-    } else {
-        auto r = to_substitution(L, 1).get_assignment(to_level(L, 2));
-        if (r) {
-            push_level(L, r->first);
-            push_justification(L, r->second);
-        } else {
-            push_nil(L); push_nil(L);
-        }
-    }
-    return 2;
-}
 static int subst_instantiate(lua_State * L) {
     if (is_expr(L, 2)) {
         auto r = to_substitution(L, 1).instantiate_metavars(to_expr(L, 2));
@@ -1783,17 +1731,12 @@ static int subst_copy(lua_State * L) {
 static const struct luaL_Reg substitution_m[] = {
     {"__gc",                   substitution_gc},
     {"copy",                   safe_function<subst_copy>},
-    {"get_expr",               safe_function<subst_get_expr>},
-    {"get_level",              safe_function<subst_get_level>},
     {"assign",                 safe_function<subst_assign>},
     {"is_assigned",            safe_function<subst_is_assigned>},
     {"is_expr_assigned",       safe_function<subst_is_expr_assigned>},
     {"is_level_assigned",      safe_function<subst_is_level_assigned>},
     {"occurs",                 safe_function<subst_occurs>},
     {"occurs_expr",            safe_function<subst_occurs_expr>},
-    {"get_expr_assignment",    safe_function<subst_get_expr_assignment>},
-    {"get_level_assignment",   safe_function<subst_get_level_assignment>},
-    {"get_assignment",         safe_function<subst_get_assignment>},
     {"instantiate",            safe_function<subst_instantiate>},
     {"instantiate_all",        safe_function<subst_instantiate_all>},
     {"for_each_expr",          safe_function<subst_for_each_expr>},
diff --git a/src/library/unifier.cpp b/src/library/unifier.cpp
index 927c1c758..9bedb486e 100644
--- a/src/library/unifier.cpp
+++ b/src/library/unifier.cpp
@@ -867,17 +867,12 @@ struct unifier_fn {
 
     expr instantiate_meta(expr e, justification & j) {
         while (true) {
-            expr const & f = get_app_fn(e);
-            if (!is_metavar(f))
+            if (auto p = m_subst.expand_metavar_app(e)) {
+                e = p->first;
+                j = mk_composite1(j, p->second);
+            } else {
                 return e;
-            name const & f_name = mlocal_name(f);
-            auto f_value = m_subst.get_expr(f_name);
-            if (!f_value)
-                return e;
-            j = mk_composite1(j, m_subst.get_expr_jst(f_name));
-            buffer<expr> args;
-            get_app_rev_args(e, args);
-            e = apply_beta(*f_value, args.size(), args.data());
+            }
         }
     }
 
diff --git a/tests/lua/subst1.lua b/tests/lua/subst1.lua
index 235ee3dad..3724e5cd1 100644
--- a/tests/lua/subst1.lua
+++ b/tests/lua/subst1.lua
@@ -20,21 +20,13 @@ s:assign(u, l)
 assert(s:is_assigned(u))
 assert(s:is_level_assigned("u"))
 assert(not s:is_expr_assigned("u"))
-assert(s:get_expr("m") == a)
 local m2 = mk_metavar("m2", Prop)
 s:assign(m2, f(m))
-print(s:get_expr("m2"))
 assert(s:is_expr_assigned("m"))
 -- m is assigned, so it is does not occur in f(m2)
 -- assert(s:occurs_expr("m", f(m2)))
-print(s:get_level("u"))
 print(s:instantiate(mk_sort(u)))
 assert(s:instantiate(mk_sort(u)) == mk_sort(l))
-assert(s:get_assignment(m) == a)
-assert(s:get_assignment(u) == l)
-assert(s:get_expr_assignment("m") == a)
-assert(s:get_level_assignment("u") == l)
-
 local s = substitution()
 local m2 = mk_metavar("m2", Prop)
 s:assign(m2, f(m))