diff --git a/ChangeLog b/ChangeLog
index ba5cfdedca..ce561d042d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2001-03-11  Roland McGrath  <roland@frob.com>
+
+	* sysdeps/mach/hurd/configure.in: Add a sanity check on $prefix.
+
 2001-03-11  Ulrich Drepper  <drepper@redhat.com>
 
 	Last-bit accurate math library implementation by IBM Haifa.
diff --git a/sysdeps/mach/hurd/configure.in b/sysdeps/mach/hurd/configure.in
index 29bb7e07b9..7daa188713 100644
--- a/sysdeps/mach/hurd/configure.in
+++ b/sysdeps/mach/hurd/configure.in
@@ -7,3 +7,7 @@ DEFINES="$DEFINES -D_LIBC_REENTRANT"
 # Don't bother trying to generate any glue code to be compatible with the
 # existing system library, because we are the only system library.
 inhibit_glue=yes
+
+if test "x$prefix" != x; then
+  AC_MSG_WARN([--prefix= (empty) is required for GNU/Hurd to work normally])
+fi