diff --git a/library/init/meta/tactic.lean b/library/init/meta/tactic.lean
index 08466c6de1..d74c519815 100644
--- a/library/init/meta/tactic.lean
+++ b/library/init/meta/tactic.lean
@@ -126,6 +126,8 @@ meta_constant defeq_simp    : expr → tactic expr
 meta_constant change        : expr → tactic unit
 /- (assert H T), adds a new goal for T, and the hypothesis (H : T := ?M) in the current goal -/
 meta_constant assert        : name → expr → tactic unit
+/- (pose H T P), adds the hypothesis (H : T) in the current goal if P has type T. -/
+meta_constant pose          : name → expr → expr → tactic unit
 /- rotate goals to the left -/
 meta_constant rotate_left   : nat → tactic unit
 meta_constant get_goals     : tactic (list expr)
diff --git a/src/library/tactic/assert_tactic.cpp b/src/library/tactic/assert_tactic.cpp
index 0fc1a588cb..91f38b3405 100644
--- a/src/library/tactic/assert_tactic.cpp
+++ b/src/library/tactic/assert_tactic.cpp
@@ -34,8 +34,35 @@ vm_obj tactic_assert(vm_obj const & n, vm_obj const & e, vm_obj const & s) {
     return assert_core(to_name(n), to_expr(e), to_tactic_state(s));
 }
 
+vm_obj pose(name const & n, expr const & e, expr const & pr, tactic_state const & s) {
+    optional<metavar_decl> g = s.get_main_goal_decl();
+    if (!g) return mk_no_goals_exception(s);
+    metavar_context mctx = s.mctx();
+    type_context ctx     = mk_type_context_for(s, mctx);
+    expr pr_type         = ctx.infer(pr);
+    if (!ctx.is_def_eq(e, pr_type)) {
+        format msg("invalid pose tactic, proof has type");
+        msg += pp_indented_expr(s, pr_type);
+        msg += line() + format("but is expected to have type");
+        msg += pp_indented_expr(s, e);
+        return mk_tactic_exception(msg, s);
+    }
+    local_context lctx   = g->get_context();
+    expr l               = lctx.mk_local_decl(n, e);
+    expr new_M           = mctx.mk_metavar_decl(lctx, g->get_type());
+    expr new_val         = mk_app(mk_lambda(n, e, mk_lazy_abstraction(new_M, mlocal_name(l))), pr);
+    mctx.assign(head(s.goals()), new_val);
+    list<expr> new_gs    = cons(new_M, tail(s.goals()));
+    return mk_tactic_success(set_mctx_goals(s, mctx, new_gs));
+}
+
+vm_obj tactic_pose(vm_obj const & n, vm_obj const & e, vm_obj const & pr, vm_obj const & s) {
+    return pose(to_name(n), to_expr(e), to_expr(pr), to_tactic_state(s));
+}
+
 void initialize_assert_tactic() {
-    DECLARE_VM_BUILTIN(name({"tactic", "assert"}),   tactic_assert);
+    DECLARE_VM_BUILTIN(name({"tactic", "assert"}), tactic_assert);
+    DECLARE_VM_BUILTIN(name({"tactic", "pose"}),   tactic_pose);
 }
 
 void finalize_assert_tactic() {