--- bc-1.06/lib/number.c
+++ bc-1.06/lib/number.c
@@ -35,6 +35,7 @@
 #include <assert.h>
 #include <stdlib.h>
 #include <ctype.h>/* Prototypes needed for external utility routines. */
+#include <string.h>
 
 #define bc_rt_warn rt_warn
 #define bc_rt_error rt_error