diff -up sudo-1.8.5rc5/common/ttysize.c.pipelist sudo-1.8.5rc5/common/ttysize.c
--- sudo-1.8.5rc5/common/ttysize.c.pipelist	2012-04-06 21:43:19.000000000 +0200
+++ sudo-1.8.5rc5/common/ttysize.c	2012-05-16 13:03:17.184034854 +0200
@@ -20,6 +20,7 @@
 
 #include <sys/types.h>
 #include <sys/ioctl.h>
+#include <sys/stat.h>
 #include <stdio.h>
 #ifdef STDC_HEADERS
 # include <stdlib.h>
@@ -71,8 +72,17 @@ get_ttysize_ioctl(int *rowp, int *colp)
 void
 get_ttysize(int *rowp, int *colp)
 {
+    struct stat st;
     debug_decl(fork_cmnd, SUDO_DEBUG_EXEC)
 
+    if (fstat(STDOUT_FILENO, &st) == 0) {
+	 if (S_ISFIFO(st.st_mode)) {
+	   *rowp = 0;
+	   *colp = 0;
+	   return;
+	 }
+    }
+
     if (get_ttysize_ioctl(rowp, colp) == -1) {
 	char *p;