diff --git a/src/sbbs3/fido.cpp b/src/sbbs3/fido.cpp
index 4851ca300b9aea3916d316c7b824b171db2acf84..19e43f699f9b077927b0b7e444f91aaaa5eaa32f 100644
--- a/src/sbbs3/fido.cpp
+++ b/src/sbbs3/fido.cpp
@@ -336,7 +336,7 @@ bool sbbs_t::netmail(const char *into, const char *title, long mode)
 		pt_zone_kludge(hdr,fido);
 		/* TZUTC (FSP-1001) */
 		int tzone=smb_tzutc(sys_timezone(&cfg));
-		char* minus="";
+		const char* minus="";
 		if(tzone<0) {
 			minus="-";
 			tzone=-tzone;