diff --git a/src/c/printer/write_symbol.d b/src/c/printer/write_symbol.d
index 681aead06..c4a7d779f 100644
--- a/src/c/printer/write_symbol.d
+++ b/src/c/printer/write_symbol.d
@@ -19,7 +19,7 @@ static bool
 potential_number_p(cl_object s, int base)
 {
   /* See ANSI 2.3.1.1 */
-  static cl_index i, l;
+  cl_index i, l;
   ecl_character c;
   /* A potential number must contain at least one digit */
   bool some_digit = FALSE;