diff --git a/m-serial-json.h b/m-serial-json.h
index 1e0f8cfe..a3efb705 100644
--- a/m-serial-json.h
+++ b/m-serial-json.h
@@ -258,13 +258,11 @@ static inline  m_serial_return_code_t
 m_serial_json_read_array_start(m_serial_read_t serial, size_t *num)
 {
   FILE *f = (FILE*) serial->data[0];
-  int final = -1;
-  fscanf(f, " [%n", &final);
+  int final1 = -1, final2 = -1;
+  fscanf(f, " [%n ]%n", &final1, &final2);
   *num = 0; // don't know the size of the array.
-  if (final < 0) return M_SERIAL_FAIL;
-  final = -1;
-  fscanf(f, " ]%n", &final);
-  return final > 0 ? M_SERIAL_OK_DONE : M_SERIAL_OK_CONTINUE;
+  // Test how much the parsing succeed.
+  return (final1 < 0) ? M_SERIAL_FAIL : (final2 < 0) ? M_SERIAL_OK_CONTINUE : M_SERIAL_OK_DONE;
 }
 
 static inline  m_serial_return_code_t
@@ -280,13 +278,11 @@ static inline  m_serial_return_code_t
 m_serial_json_read_map_start(m_serial_read_t serial, size_t *num)
 {
   FILE *f = (FILE*) serial->data[0];
-  int final = -1;
-  fscanf(f, " {%n", &final);
+  int final1 = -1, final2 = -1;
+  fscanf(f, " {%n }%n", &final1, &final2);
   *num = 0; // don't know the size of the map.
-  if (final < 0) return M_SERIAL_FAIL;
-  final = -1;
-  fscanf(f, " }%n", &final);
-  return final > 0 ? M_SERIAL_OK_DONE : M_SERIAL_OK_CONTINUE;
+  // Test how much the parsing succeed.
+  return (final1 < 0) ? M_SERIAL_FAIL : (final2 < 0) ? M_SERIAL_OK_CONTINUE : M_SERIAL_OK_DONE;
 }
 
 static inline  m_serial_return_code_t