diff --git a/src/library/blast/CMakeLists.txt b/src/library/blast/CMakeLists.txt
index 0549b34f7..dbeb4b3a0 100644
--- a/src/library/blast/CMakeLists.txt
+++ b/src/library/blast/CMakeLists.txt
@@ -1 +1 @@
-add_library(blast OBJECT state.cpp expr.cpp hypothesis.cpp)
+add_library(blast OBJECT state.cpp expr.cpp)
diff --git a/src/library/blast/goal.h b/src/library/blast/goal.h
index a9a47eb9b..9d80f5e7f 100644
--- a/src/library/blast/goal.h
+++ b/src/library/blast/goal.h
@@ -14,8 +14,9 @@ namespace blast {
 class goal {
     typedef rb_map<unsigned, hypothesis, unsigned_cmp> context;
     friend class state;
-    unsigned m_next;
-    context  m_context;
+    unsigned      m_next;
+    context       m_context;
+    expr          m_type;
     expr const & mk_lref(expr const & type, optional<expr> const & value);
 public:
     goal():m_next(0) {}
diff --git a/src/library/blast/hypothesis.cpp b/src/library/blast/hypothesis.cpp
deleted file mode 100644
index 2674b362e..000000000
--- a/src/library/blast/hypothesis.cpp
+++ /dev/null
@@ -1,50 +0,0 @@
-/*
-Copyright (c) 2015 Microsoft Corporation. All rights reserved.
-Released under Apache 2.0 license as described in the file LICENSE.
-
-Author: Leonardo de Moura
-*/
-#include "library/blast/hypothesis.h"
-
-namespace lean {
-namespace blast {
-struct justification_idx_gen {
-    unsigned       m_next_idx;
-    list<unsigned> m_free_list;
-public:
-    justification_idx_gen():m_next_idx(0) {}
-    void recycle(unsigned idx) {
-        m_free_list = cons(idx, m_free_list);
-    }
-    unsigned next() {
-        if (m_free_list) {
-            unsigned r = head(m_free_list);
-            m_free_list = tail(m_free_list);
-            return r;
-        } else {
-            unsigned r = m_next_idx;
-            m_next_idx++;
-            return r;
-        }
-    }
-};
-
-MK_THREAD_LOCAL_GET_DEF(justification_idx_gen, get_justification_idx_gen)
-
-justification_cell::justification_cell():m_rc(0) {
-    m_idx = get_justification_idx_gen().next();
-}
-
-void justification_cell::dealloc() {
-    get_justification_idx_gen().recycle(m_idx);
-    delete this;
-}
-
-justification::justification():m_ptr(nullptr) {}
-justification::justification(justification_cell & ptr):m_ptr(&ptr) { if (m_ptr) m_ptr->inc_ref(); }
-justification::justification(justification const & s):m_ptr(s.m_ptr) { if (m_ptr) m_ptr->inc_ref(); }
-justification::justification(justification && s):m_ptr(s.m_ptr) { s.m_ptr = nullptr; }
-justification::~justification() { if (m_ptr) m_ptr->dec_ref(); }
-justification & justification::operator=(justification const & s) { LEAN_COPY_REF(s); }
-justification & justification::operator=(justification && s) { LEAN_MOVE_REF(s); }
-}}
diff --git a/src/library/blast/hypothesis.h b/src/library/blast/hypothesis.h
index 65324fa26..228a94eda 100644
--- a/src/library/blast/hypothesis.h
+++ b/src/library/blast/hypothesis.h
@@ -15,32 +15,6 @@ class hypothesis;
 class state;
 class goal;
 
-class justification_cell {
-    MK_LEAN_RC();
-    unsigned m_idx;
-    void dealloc();
-public:
-    justification_cell();
-    virtual ~justification_cell() {}
-    virtual expr to_expr(hypothesis const &) const = 0;
-    /** \brief Return thread local unique identifier associated with justification object */
-    unsigned get_idx() const { return m_idx; }
-};
-
-class justification {
-    justification_cell * m_ptr;
-public:
-    justification();
-    justification(justification_cell & c);
-    justification(justification const & s);
-    justification(justification && s);
-    ~justification();
-
-    justification & operator=(justification const & s);
-    justification & operator=(justification && s);
-    expr to_expr(hypothesis const & h) const { return m_ptr->to_expr(h); }
-};
-
 typedef rb_tree<unsigned, unsigned_cmp> hypothesis_set;
 
 class hypothesis {
@@ -51,7 +25,7 @@ class hypothesis {
     hypothesis_set m_forward_deps;
     expr           m_type;
     optional<expr> m_value;
-    justification  m_jst;
+    optional<expr> m_justification;
 public:
     hypothesis();
     bool is_active() const { return m_active; }
@@ -60,7 +34,7 @@ public:
     hypothesis_set const & get_forward_deps() const { return m_forward_deps; }
     expr const & get_type() const { return m_type; }
     optional<expr> const & get_value() const { return m_value; }
-    justification const & get_justification() const { return m_jst; }
+    optional<expr> const & get_justification() const { return m_justification; }
 };
 }
 }
diff --git a/src/library/blast/state.h b/src/library/blast/state.h
index 6afa2edac..6f85d935e 100644
--- a/src/library/blast/state.h
+++ b/src/library/blast/state.h
@@ -5,9 +5,19 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Author: Leonardo de Moura
 */
 #pragma once
+#include "util/rb_map.h"
 #include "kernel/expr.h"
+#include "library/blast/hypothesis.h"
+
 namespace lean {
 namespace blast {
+class metavar_decl {
+    hypothesis_set m_context;
+    expr           m_type;
+};
+
 class state {
+    typedef rb_map<unsigned, metavar_decl, unsigned_cmp> metavar_decls;
+    metavar_decls m_metavar_decls;
 };
 }}