diff --git a/lib/lib.error.c b/lib/lib.error.c
index b364eda51bc..cbd978cf489 100644
--- a/lib/lib.error.c
+++ b/lib/lib.error.c
@@ -113,13 +113,14 @@ void vlogmsg(int msglevel, const char *mesg, va_list ap)
 	bufferlen = strlen(timestring)+strlen(progname_escaped)+strlen(mesg)+20;
 	buffer = (char *)malloc(bufferlen);
 	if ( buffer==NULL ) abort();
-	progname_unformatted = (char *)malloc(1+strlen(progname_escaped));
+	progname_unformatted = (char *)malloc(1+2*strlen(progname_escaped));
 	size_t str_tmp_pos, esc_tmp_pos;
 	char ctmp;
 	for(str_tmp_pos=0; str_tmp_pos<strlen(progname_escaped); str_tmp_pos++) {
 		ctmp = progname_escaped[str_tmp_pos];
 		if ( ctmp!='%' ) {
 			progname_unformatted[esc_tmp_pos++] = 'c';
+			progname_unformatted[esc_tmp_pos++] = ctmp;
 		}
 	}
 	progname_unformatted[esc_tmp_pos] = 0;