diff --git a/doc/sudo.man.in b/doc/sudo.man.in
index fcefabdd4..bcc1a7f70 100644
--- a/doc/sudo.man.in
+++ b/doc/sudo.man.in
@@ -25,7 +25,7 @@
 .nr BA @BAMAN@
 .nr LC @LCMAN@
 .nr PS @PSMAN@
-.TH "SUDO" "@mansectsu@" "May 7, 2020" "Sudo @PACKAGE_VERSION@" "System Manager's Manual"
+.TH "SUDO" "@mansectsu@" "July 22, 2020" "Sudo @PACKAGE_VERSION@" "System Manager's Manual"
 .nh
 .if n .ad l
 .SH "NAME"
@@ -354,6 +354,8 @@ If the specified file does not exist, it will be created.
 Note that unlike most commands run by
 \fIsudo\fR,
 the editor is run with the invoking user's environment unmodified.
+If the temporary file becomes empty after editing, the user will
+be prompted before it is installed.
 If, for some reason,
 \fBsudo\fR
 is unable to update a file with its edited version, the user will
diff --git a/doc/sudo.mdoc.in b/doc/sudo.mdoc.in
index 57295bb27..0f452420a 100644
--- a/doc/sudo.mdoc.in
+++ b/doc/sudo.mdoc.in
@@ -24,7 +24,7 @@
 .nr BA @BAMAN@
 .nr LC @LCMAN@
 .nr PS @PSMAN@
-.Dd May 7, 2020
+.Dd July 22, 2020
 .Dt SUDO @mansectsu@
 .Os Sudo @PACKAGE_VERSION@
 .Sh NAME
@@ -336,6 +336,8 @@ If the specified file does not exist, it will be created.
 Note that unlike most commands run by
 .Em sudo ,
 the editor is run with the invoking user's environment unmodified.
+If the temporary file becomes empty after editing, the user will
+be prompted before it is installed.
 If, for some reason,
 .Nm
 is unable to update a file with its edited version, the user will
diff --git a/src/copy_file.c b/src/copy_file.c
index 0db52630f..9aeb1f92a 100644
--- a/src/copy_file.c
+++ b/src/copy_file.c
@@ -86,6 +86,17 @@ sudo_copy_file(const char *src, int src_fd, off_t src_len, const char *dst,
     ssize_t nwritten, nread;
     debug_decl(sudo_copy_file, SUDO_DEBUG_UTIL);
 
+    /* Prompt the user before zeroing out an existing file. */
+    if (dst_len > 0 && src_len == 0) {
+	fprintf(stderr, U_("%s: truncate %s to zero bytes? (y/n) [n] "),
+	    getprogname(), dst);
+	if (fgets(buf, sizeof(buf), stdin) == NULL ||
+		(buf[0] != 'y' && buf[0] != 'Y')) {
+	    sudo_warnx(U_("not overwriting %s"), dst);
+	    debug_return_int(0);
+	}
+    }
+
     /* Extend the file to the new size if larger before copying. */
     if (dst_len > 0 && src_len > dst_len) {
 	if (sudo_extend_file(dst_fd, dst, src_len) == -1)