diff --git a/st.c b/st.c
index 8237d78..f9ac1f7 100644
--- a/st.c
+++ b/st.c
@@ -1226,7 +1226,7 @@ ttynew(void) {
 				  open(opt_io, O_WRONLY | O_CREAT, 0666);
 			if(iofd < 0) {
 				fprintf(stderr, "Error opening %s:%s\n",
-					opt_io, strerror(errno));
+					opt_io, SERRNO);
 			}
 		}
 	}
@@ -2239,7 +2239,7 @@ void
 tprinter(char *s, size_t len) {
 	if(iofd != -1 && xwrite(iofd, s, len) < 0) {
 		fprintf(stderr, "Error writing in %s:%s\n",
-			opt_io, strerror(errno));
+			opt_io, SERRNO);
 		close(iofd);
 		iofd = -1;
 	}