diff --git a/exec.cpp b/exec.cpp
index 60b46ab9a..e282f72fb 100644
--- a/exec.cpp
+++ b/exec.cpp
@@ -516,9 +516,6 @@ static void internal_exec_helper(parser_t &parser,
     std::vector<int> opened_fds;
     bool transmorgrified = io_transmogrify(ios, &morphed_chain, &opened_fds);
 
-    int is_block_old=is_block;
-    is_block=1;
-
     /*
       Did the transmogrification fail - if so, set error status and return
     */
@@ -528,6 +525,9 @@ static void internal_exec_helper(parser_t &parser,
         return;
     }
 
+    int is_block_old=is_block;
+    is_block=1;
+
     signal_unblock();
 
     if (node_offset == NODE_OFFSET_INVALID)
diff --git a/tests/gen_output.fish b/tests/gen_output.fish
index 49e15bfdc..7bf7f3ec3 100755
--- a/tests/gen_output.fish
+++ b/tests/gen_output.fish
@@ -1,4 +1,4 @@
-#!/usr/bin/fish
+#!/usr/bin/env fish
 
 #
 # Generate output for a test script
@@ -14,4 +14,4 @@ for i in $argv
 
 	fish <$i >$template_out ^$template_err
 	echo $status >$template_status
-end
\ No newline at end of file
+end
diff --git a/tests/status.err b/tests/status.err
new file mode 100644
index 000000000..91645c95f
--- /dev/null
+++ b/tests/status.err
@@ -0,0 +1,2 @@
+fish: An error occurred while redirecting file '/'
+open: Is a directory
diff --git a/tests/status.in b/tests/status.in
new file mode 100644
index 000000000..14dff2320
--- /dev/null
+++ b/tests/status.in
@@ -0,0 +1,9 @@
+# vim: set filetype=fish:
+
+# Issue #1728
+# Bad file redirection on a block causes `status --is-block` to return 0 forever.
+begin; end >/ # / is a directory, it can't be opened for writing
+status -b
+and echo 'block'
+
+true
diff --git a/tests/status.out b/tests/status.out
new file mode 100644
index 000000000..e69de29bb
diff --git a/tests/status.status b/tests/status.status
new file mode 100644
index 000000000..573541ac9
--- /dev/null
+++ b/tests/status.status
@@ -0,0 +1 @@
+0
diff --git a/tests/top.out b/tests/top.out
index a62ec0474..87d1ee313 100644
--- a/tests/top.out
+++ b/tests/top.out
@@ -2,6 +2,7 @@ Testing high level script functionality
 File expansion.in tested ok
 File printf.in tested ok
 File read.in tested ok
+File status.in tested ok
 File test1.in tested ok
 File test2.in tested ok
 File test3.in tested ok