diff --git a/src/ast/expr_substitution.h b/src/ast/expr_substitution.h
index 03e96db42..f71e7d232 100644
--- a/src/ast/expr_substitution.h
+++ b/src/ast/expr_substitution.h
@@ -51,6 +51,8 @@ public:
     void reset();
     void cleanup();
 
+    obj_map<expr, expr*> const sub() const { return m_subst; }
+
     std::ostream& display(std::ostream& out);
 };
 
diff --git a/src/ast/rewriter/th_rewriter.cpp b/src/ast/rewriter/th_rewriter.cpp
index 4937e480c..b4521a216 100644
--- a/src/ast/rewriter/th_rewriter.cpp
+++ b/src/ast/rewriter/th_rewriter.cpp
@@ -30,6 +30,7 @@ Notes:
 #include "ast/rewriter/seq_rewriter.h"
 #include "ast/rewriter/rewriter_def.h"
 #include "ast/rewriter/var_subst.h"
+#include "ast/rewriter/expr_safe_replace.h"
 #include "ast/expr_substitution.h"
 #include "ast/ast_smt2_pp.h"
 #include "ast/ast_pp.h"
@@ -50,6 +51,7 @@ struct th_rewriter_cfg : public default_rewriter_cfg {
     recfun_rewriter     m_rec_rw;
     arith_util          m_a_util;
     bv_util             m_bv_util;
+    expr_ref_vector     m_pinned;
     unsigned long long  m_max_memory; // in bytes
     unsigned            m_max_steps;
     bool                m_pull_cheap_ite;
@@ -663,6 +665,20 @@ struct th_rewriter_cfg : public default_rewriter_cfg {
         return result;
     }
 
+    void apply_subst(ptr_buffer<expr>& patterns) {
+        if (!m_subst)
+            return;
+        expr_ref tmp(m());
+        expr_safe_replace rep(m());
+        for (auto kv : m_subst->sub())
+            rep.insert(kv.m_key, kv.m_value);
+        for (unsigned i = 0; i < patterns.size(); ++i) {
+            rep(patterns[i], tmp);
+            m_pinned.push_back(tmp);
+            patterns[i] = tmp;
+        }
+    }
+
 
     bool reduce_quantifier(quantifier * old_q,
                            expr * new_body,
@@ -721,9 +737,12 @@ struct th_rewriter_cfg : public default_rewriter_cfg {
             remove_duplicates(new_patterns_buf);
             remove_duplicates(new_no_patterns_buf);
 
+            apply_subst(new_patterns_buf);
+
             q1 = m().update_quantifier(old_q,
                                        new_patterns_buf.size(), new_patterns_buf.c_ptr(), new_no_patterns_buf.size(), new_no_patterns_buf.c_ptr(),
                                        new_body);
+            m_pinned.reset();
             TRACE("reduce_quantifier", tout << mk_ismt2_pp(old_q, m()) << "\n----->\n" << mk_ismt2_pp(q1, m()) << "\n";);
             SASSERT(is_well_sorted(m(), q1));
             if (m().proofs_enabled() && q1 != old_q) {
@@ -760,6 +779,7 @@ struct th_rewriter_cfg : public default_rewriter_cfg {
         m_rec_rw(m),
         m_a_util(m),
         m_bv_util(m),
+        m_pinned(m),
         m_used_dependencies(m),
         m_subst(nullptr) {
         updt_local_params(p);