diff --git a/examples/c/lexcalc/scan.l b/examples/c/lexcalc/scan.l
index fc73f3b0..815f7782 100644
--- a/examples/c/lexcalc/scan.l
+++ b/examples/c/lexcalc/scan.l
@@ -4,6 +4,7 @@
 %option nodefault noinput nounput noyywrap
 
 %{
+#include <errno.h> /* errno, ERANGE */
 #include <limits.h> /* INT_MIN */
 #include <stdlib.h> /* strtol */