diff --git a/src/ast/sls/bv_sls_eval.cpp b/src/ast/sls/bv_sls_eval.cpp
index 4dbd4b11f..f64326d22 100644
--- a/src/ast/sls/bv_sls_eval.cpp
+++ b/src/ast/sls/bv_sls_eval.cpp
@@ -429,6 +429,8 @@ namespace bv {
             break;
         }
         case OP_CONCAT: {
+            if (e->get_num_args() != 2)
+                verbose_stream() << mk_bounded_pp(e, m) << "\n";
             SASSERT(e->get_num_args() == 2);
             auto const& a = wval0(e->get_arg(0));
             auto const& b = wval0(e->get_arg(1));
diff --git a/src/ast/sls/bv_sls_terms.cpp b/src/ast/sls/bv_sls_terms.cpp
index 41ab0bf19..8702c3c48 100644
--- a/src/ast/sls/bv_sls_terms.cpp
+++ b/src/ast/sls/bv_sls_terms.cpp
@@ -18,6 +18,7 @@ Author:
     
 --*/
 
+#include "ast/ast_ll_pp.h"
 #include "ast/sls/bv_sls.h"
 
 namespace bv {
@@ -60,13 +61,15 @@ namespace bv {
     }
 
     void sls_terms::ensure_binary_core(expr* e) {
+        if (m_translated.get(e->get_id(), nullptr))
+            return;
+        
         app* a = to_app(e);
         auto arg = [&](unsigned i) {
             return m_translated.get(a->get_arg(i)->get_id());
         };
         unsigned num_args = a->get_num_args();
         expr_ref r(m);
-        expr* x, * y;
 #define FOLD_OP(oper)           \
         r = arg(0);             \
         for (unsigned i = 1; i < num_args; ++i)\
@@ -106,20 +109,20 @@ namespace bv {
                     es.push_back(m.mk_not(m.mk_eq(arg(i), arg(j))));
             r = m.mk_and(es);
         }
-        else if (bv.is_bv_sdiv(e, x, y) || bv.is_bv_sdiv0(e, x, y) || bv.is_bv_sdivi(e, x, y)) {
-            r = mk_sdiv(x, y);
+        else if (bv.is_bv_sdiv(e) || bv.is_bv_sdiv0(e) || bv.is_bv_sdivi(e)) {
+            r = mk_sdiv(arg(0), arg(1));
         }
-        else if (bv.is_bv_smod(e, x, y) || bv.is_bv_smod0(e, x, y) || bv.is_bv_smodi(e, x, y)) {
-            r = mk_smod(x, y);
+        else if (bv.is_bv_smod(e) || bv.is_bv_smod0(e) || bv.is_bv_smodi(e)) {
+            r = mk_smod(arg(0), arg(1));
         }
-        else if (bv.is_bv_srem(e, x, y) || bv.is_bv_srem0(e, x, y) || bv.is_bv_sremi(e, x, y)) {
-            r = mk_srem(x, y);
+        else if (bv.is_bv_srem(e) || bv.is_bv_srem0(e) || bv.is_bv_sremi(e)) {
+            r = mk_srem(arg(0), arg(1));
         }
         else {
             for (unsigned i = 0; i < num_args; ++i)
-                m_todo.push_back(arg(i));
-            r = m.mk_app(a->get_decl(), num_args, m_todo.data());
-            m_todo.reset();
+                m_args.push_back(arg(i));
+            r = m.mk_app(a->get_decl(), num_args, m_args.data());
+            m_args.reset();
         }
         m_translated.setx(e->get_id(), r);
     }
diff --git a/src/ast/sls/bv_sls_terms.h b/src/ast/sls/bv_sls_terms.h
index 2f9aee225..3baffc78e 100644
--- a/src/ast/sls/bv_sls_terms.h
+++ b/src/ast/sls/bv_sls_terms.h
@@ -31,7 +31,7 @@ namespace bv {
     class sls_terms {
         ast_manager&        m;
         bv_util             bv;
-        ptr_vector<expr>    m_todo;
+        ptr_vector<expr>    m_todo, m_args;
         expr_ref_vector     m_assertions, m_pinned, m_translated;
         app_ref_vector      m_terms;
         vector<ptr_vector<expr>> m_parents;