diff --git a/src/include/ngspice/wordlist.h b/src/include/ngspice/wordlist.h
index a591b58c5..713ef26a2 100644
--- a/src/include/ngspice/wordlist.h
+++ b/src/include/ngspice/wordlist.h
@@ -1,6 +1,7 @@
 #ifndef ngspice_WORDLIST_H
 #define ngspice_WORDLIST_H
 
+#include <stdio.h>
 
 /* Doubly linked lists of words. */
 struct wordlist {