diff --git a/src/reader.c b/src/reader.c
index 40f367ee..54c06de6 100644
--- a/src/reader.c
+++ b/src/reader.c
@@ -93,7 +93,7 @@ reader_read_identifier_or_number (int c)
       n = n + c - '0';
       c = readchar ();
     }
-  if (reader_end_of_word_p (c))
+  if (reader_end_of_word_p (c) != 0)
     {
       unreadchar (c);
       if (negative_p != 0)