diff --git a/command/fs.go b/command/fs.go
index df1bbf91d..7c4a0800f 100644
--- a/command/fs.go
+++ b/command/fs.go
@@ -103,7 +103,11 @@ func (f *FSCommand) Run(args []string) int {
 		} else {
 			f.Ui.Error("allocation ID is required")
 		}
+		return 1
+	}
 
+	if len(args) > 2 {
+		f.Ui.Error(f.Help())
 		return 1
 	}
 
diff --git a/command/fs_test.go b/command/fs_test.go
new file mode 100644
index 000000000..7edecd939
--- /dev/null
+++ b/command/fs_test.go
@@ -0,0 +1,83 @@
+package command
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/mitchellh/cli"
+)
+
+func TestFSCommand_Implements(t *testing.T) {
+	var _ cli.Command = &FSCommand{}
+}
+
+func TestFSCommand_Fails(t *testing.T) {
+	srv, _, url := testServer(t, nil)
+	defer srv.Stop()
+
+	ui := new(cli.MockUi)
+	cmd := &FSCommand{Meta: Meta{Ui: ui}}
+
+	// Fails on lack of job ID
+	if code := cmd.Run([]string{"-job"}); code != 1 {
+		t.Fatalf("expected exit code 1, got: %d", code)
+	}
+	if out := ui.ErrorWriter.String(); !strings.Contains(out, "job ID is required") {
+		t.Fatalf("expected help output, got: %s", out)
+	}
+	ui.ErrorWriter.Reset()
+
+	// Fails on lack of allocation ID
+	if code := cmd.Run([]string{}); code != 1 {
+		t.Fatalf("expected exit code 1, got: %d", code)
+	}
+	if out := ui.ErrorWriter.String(); !strings.Contains(out, "allocation ID is required") {
+		t.Fatalf("expected help output, got: %s", out)
+	}
+	ui.ErrorWriter.Reset()
+
+	// Fails on misuse
+	if code := cmd.Run([]string{"some", "bad", "args"}); code != 1 {
+		t.Fatalf("expected exit code 1, got: %d", code)
+	}
+	if out := ui.ErrorWriter.String(); !strings.Contains(out, cmd.Help()) {
+		t.Fatalf("expected help output, got: %s", out)
+	}
+	ui.ErrorWriter.Reset()
+
+	// Fails on connection failure
+	if code := cmd.Run([]string{"-address=nope", "foobar"}); code != 1 {
+		t.Fatalf("expected exit code 1, got: %d", code)
+	}
+	if out := ui.ErrorWriter.String(); !strings.Contains(out, "Error querying allocation") {
+		t.Fatalf("expected failed query error, got: %s", out)
+	}
+	ui.ErrorWriter.Reset()
+
+	// Fails on missing alloc
+	if code := cmd.Run([]string{"-address=" + url, "26470238-5CF2-438F-8772-DC67CFB0705C"}); code != 1 {
+		t.Fatalf("expected exit 1, got: %d", code)
+	}
+	if out := ui.ErrorWriter.String(); !strings.Contains(out, "No allocation(s) with prefix or id") {
+		t.Fatalf("expected not found error, got: %s", out)
+	}
+	ui.ErrorWriter.Reset()
+
+	// Fail on identifier with too few characters
+	if code := cmd.Run([]string{"-address=" + url, "2"}); code != 1 {
+		t.Fatalf("expected exit 1, got: %d", code)
+	}
+	if out := ui.ErrorWriter.String(); !strings.Contains(out, "must contain at least two characters.") {
+		t.Fatalf("expected too few characters error, got: %s", out)
+	}
+	ui.ErrorWriter.Reset()
+
+	// Identifiers with uneven length should produce a query result
+	if code := cmd.Run([]string{"-address=" + url, "123"}); code != 1 {
+		t.Fatalf("expected exit 1, got: %d", code)
+	}
+	if out := ui.ErrorWriter.String(); !strings.Contains(out, "No allocation(s) with prefix or id") {
+		t.Fatalf("expected not found error, got: %s", out)
+	}
+
+}