diff --git a/src/api/api_context.cpp b/src/api/api_context.cpp
index 673d0b1c9..cc2a13aed 100644
--- a/src/api/api_context.cpp
+++ b/src/api/api_context.cpp
@@ -379,11 +379,13 @@ extern "C" {
         Z3_TRY;
         LOG_Z3_dec_ref(c, a);
         RESET_ERROR_CODE();
-        if (to_ast(a)->get_ref_count() == 0) {
+        if (a && to_ast(a)->get_ref_count() == 0) {
             SET_ERROR_CODE(Z3_DEC_REF_ERROR, nullptr);
             return;
         }
-        mk_c(c)->m().dec_ref(to_ast(a));
+        if (a) {
+            mk_c(c)->m().dec_ref(to_ast(a));
+        }
 
         Z3_CATCH;
     }
diff --git a/src/api/api_model.cpp b/src/api/api_model.cpp
index e9dd3580b..939cccdca 100644
--- a/src/api/api_model.cpp
+++ b/src/api/api_model.cpp
@@ -206,9 +206,8 @@ extern "C" {
         ptr_vector<expr> const & universe = to_model_ref(m)->get_universe(to_sort(s));
         Z3_ast_vector_ref * v = alloc(Z3_ast_vector_ref, *mk_c(c), mk_c(c)->m());
         mk_c(c)->save_object(v);
-        unsigned sz = universe.size();
-        for (unsigned i = 0; i < sz; i++) {
-            v->m_ast_vector.push_back(universe[i]);
+        for (expr * e : universe) {
+            v->m_ast_vector.push_back(e);
         }
         RETURN_Z3(of_ast_vector(v));
         Z3_CATCH_RETURN(nullptr);
@@ -230,7 +229,7 @@ extern "C" {
         Z3_TRY;
         LOG_Z3_is_as_array(c, a);
         RESET_ERROR_CODE();
-        return is_expr(to_ast(a)) && is_app_of(to_expr(a), mk_c(c)->get_array_fid(), OP_AS_ARRAY);
+        return a && is_expr(to_ast(a)) && is_app_of(to_expr(a), mk_c(c)->get_array_fid(), OP_AS_ARRAY);
         Z3_CATCH_RETURN(Z3_FALSE);
     }
     
@@ -238,7 +237,7 @@ extern "C" {
         Z3_TRY;
         LOG_Z3_get_as_array_func_decl(c, a);
         RESET_ERROR_CODE();
-        if (is_expr(to_ast(a)) && is_app_of(to_expr(a), mk_c(c)->get_array_fid(), OP_AS_ARRAY)) {
+        if (a && is_expr(to_ast(a)) && is_app_of(to_expr(a), mk_c(c)->get_array_fid(), OP_AS_ARRAY)) {
             RETURN_Z3(of_func_decl(to_func_decl(to_app(a)->get_decl()->get_parameter(0).get_ast())));
         }
         else {
@@ -252,6 +251,7 @@ extern "C" {
         Z3_TRY;
         LOG_Z3_add_func_interp(c, m, f, else_val);
         RESET_ERROR_CODE();
+		CHECK_NON_NULL(f, nullptr);
         func_decl* d = to_func_decl(f);
         model* mdl = to_model_ref(m);
         Z3_func_interp_ref * f_ref = alloc(Z3_func_interp_ref, *mk_c(c), mdl); 
@@ -268,7 +268,7 @@ extern "C" {
         LOG_Z3_add_const_interp(c, m, f, a);
         RESET_ERROR_CODE();
         func_decl* d = to_func_decl(f);
-        if (d->get_arity() != 0) {
+        if (!d || d->get_arity() != 0) {
             SET_ERROR_CODE(Z3_INVALID_ARG, nullptr);
         }
         else {
diff --git a/src/smt/smt_model_generator.cpp b/src/smt/smt_model_generator.cpp
index 190f7f79e..a4b3029e2 100644
--- a/src/smt/smt_model_generator.cpp
+++ b/src/smt/smt_model_generator.cpp
@@ -438,8 +438,7 @@ namespace smt {
         }
     }
 
-    extra_fresh_value * model_generator::mk_extra_fresh_value(sort * s) {
-        SASSERT(s->is_infinite());
+    extra_fresh_value * model_generator::mk_extra_fresh_value(sort * s) {        
         extra_fresh_value * r = alloc(extra_fresh_value, s, m_fresh_idx);
         m_fresh_idx++;
         m_extra_fresh_values.push_back(r);
diff --git a/src/smt/theory_bv.cpp b/src/smt/theory_bv.cpp
index a9b3e6131..33207d15a 100644
--- a/src/smt/theory_bv.cpp
+++ b/src/smt/theory_bv.cpp
@@ -850,6 +850,7 @@ namespace smt {
     }
 
     bool theory_bv::internalize_term(app * term) {
+        scoped_suspend_rlimit _suspend_cancel(get_manager().limit());
         try {
         SASSERT(term->get_family_id() == get_family_id());
         TRACE("bv", tout << "internalizing term: " << mk_bounded_pp(term, get_manager()) << "\n";);
@@ -910,7 +911,7 @@ namespace smt {
         }
         }
         catch (z3_exception& ex) {
-            IF_VERBOSE(1, verbose_stream() << ex.msg() << "\n";);
+            IF_VERBOSE(1, verbose_stream() << "internalize_term: " << ex.msg() << "\n";);
             throw;
         }
     }
diff --git a/src/util/rlimit.h b/src/util/rlimit.h
index 60d26be7f..cc022a963 100644
--- a/src/util/rlimit.h
+++ b/src/util/rlimit.h
@@ -65,12 +65,14 @@ public:
 
 class scoped_suspend_rlimit {
     reslimit & m_limit;
+    bool       m_suspend;
 public:
     scoped_suspend_rlimit(reslimit& r): m_limit(r) {
+        m_suspend = r.m_suspend;
         r.m_suspend = true;
     }
     ~scoped_suspend_rlimit() {
-        m_limit.m_suspend = false;
+        m_limit.m_suspend = m_suspend;
     }
 };