--- a/stage4/generate_c/generate_c_st.cc	Tue Dec 14 09:02:38 2021 +0100
+++ b/stage4/generate_c/generate_c_st.cc	Tue Feb 15 10:34:23 2022 +0100
@@ -1341,9 +1341,9 @@
   s4o.indent_right();
   symbol->statement_list->accept(*this);
   s4o.indent_left();
-  s4o.print(s4o.indent_spaces); s4o.print("} while(");
+  s4o.print(s4o.indent_spaces); s4o.print("} while(!(");
   symbol->expression->accept(*this);
-  s4o.print(")");
+  s4o.print("))");
   return NULL;
 }