diff --git a/examples/tptp/tptp5.cpp b/examples/tptp/tptp5.cpp
index 2a90b5a3f..d40aa93e9 100644
--- a/examples/tptp/tptp5.cpp
+++ b/examples/tptp/tptp5.cpp
@@ -2083,7 +2083,7 @@ bool parse_is_sat_line(char const* line, bool& is_sat) {
         return true;
     }
     return false;
-    
+}    
 
 bool parse_is_sat(char const* filename, bool& is_sat) {
     std::ifstream is(filename);
diff --git a/src/api/c++/z3++.h b/src/api/c++/z3++.h
index 11c80a2be..3c925e95c 100644
--- a/src/api/c++/z3++.h
+++ b/src/api/c++/z3++.h
@@ -1111,7 +1111,8 @@ namespace z3 {
     }
 
     inline expr concat(expr const& a, expr const& b) {
-        Z3_ast r = Z3_mk_concat(ctx, (Z3_app) a, (Z3_app) b);
+        context& ctx = a.ctx();
+        Z3_ast r = Z3_mk_concat(ctx, (Z3_ast) a, (Z3_ast) b);
         ctx.check_error();
         return expr(ctx, r);
     }