diff --git a/cmd/exec.go b/cmd/exec.go
index c1e3de3af6..c59e36421d 100644
--- a/cmd/exec.go
+++ b/cmd/exec.go
@@ -51,7 +51,10 @@ After: Decision Logs
 By default, the 'exec' command executes the "default decision" (specified in
 the OPA configuration) against each input file. This can be overridden by
 specifying the --decision argument and pointing at a specific policy decision,
-e.g., opa exec --decision /foo/bar/baz ...`,
+e.g., opa exec --decision /foo/bar/baz ...
+
+Alternative Usage:
+  ` + RootCommand.Use + ` exec [<path> [...]] --stdin-input [flags]`,
 
 		PreRunE: func(cmd *cobra.Command, _ []string) error {
 			return env.CmdFlags.CheckEnvironmentVariables(cmd)
diff --git a/cmd/internal/exec/exec.go b/cmd/internal/exec/exec.go
index ed8f940fe1..8748b4dda1 100644
--- a/cmd/internal/exec/exec.go
+++ b/cmd/internal/exec/exec.go
@@ -36,15 +36,20 @@ func Exec(ctx context.Context, opa *sdk.OPA, params *Params) error {
 
 	r = &jsonReporter{w: params.Output, buf: make([]result, 0), ctx: &ctx, opa: opa, params: params, decisionFunc: opa.Decision}
 
-	var err error
 	if params.StdIn {
-		err = execOnStdIn()
-	} else {
-		err = execOnInputFiles(params)
+		if err := execOnStdIn(); err != nil {
+			return err
+		}
 	}
-	if err != nil {
+
+	if err := execOnInputFiles(params); err != nil {
 		return err
 	}
+
+	if err := r.Close(); err != nil {
+		return err
+	}
+
 	return r.ReportFailure()
 }
 
@@ -59,7 +64,7 @@ func execOnStdIn() error {
 		return errors.New("cannot execute on empty input; please enter valid json or yaml when using the --stdin-input flag")
 	}
 	r.StoreDecision(&input, stdInPath)
-	return r.Close()
+	return nil
 }
 
 type fileListItem struct {
@@ -87,7 +92,7 @@ func execOnInputFiles(params *Params) error {
 		}
 		r.StoreDecision(input, item.Path)
 	}
-	return r.Close()
+	return nil
 }
 
 func listAllPaths(roots []string) chan fileListItem {
diff --git a/cmd/internal/exec/exec_test.go b/cmd/internal/exec/exec_test.go
index 08f6f85242..2c2476c27f 100644
--- a/cmd/internal/exec/exec_test.go
+++ b/cmd/internal/exec/exec_test.go
@@ -79,7 +79,7 @@ func TestExec(t *testing.T) {
 		files       map[string]string
 		stdIn       bool
 		input       string
-		assertion   func(err error)
+		assertion   func(t *testing.T, buf string, err error)
 	}{
 		{
 			description: "should read from valid JSON file and not raise an error",
@@ -96,7 +96,7 @@ func TestExec(t *testing.T) {
 			test_fun
 		}`,
 			},
-			assertion: func(err error) {
+			assertion: func(t *testing.T, _ string, err error) {
 				if err != nil {
 					t.Fatalf("unexpected error raised: %q", err.Error())
 				}
@@ -117,7 +117,7 @@ func TestExec(t *testing.T) {
 			test_fun
 		}`,
 			},
-			assertion: func(err error) {
+			assertion: func(t *testing.T, _ string, err error) {
 				if err == nil {
 					t.Fatalf("expected error, found none")
 				}
@@ -142,12 +142,58 @@ func TestExec(t *testing.T) {
 			},
 			stdIn: true,
 			input: `{"foo": 7}`,
-			assertion: func(err error) {
+			assertion: func(t *testing.T, _ string, err error) {
 				if err != nil {
 					t.Fatalf("unexpected error raised: %q", err.Error())
 				}
 			},
 		},
+		{
+			description: "should read from files and stdin-input if flag is set",
+			files: map[string]string{
+				"files/test.json": `{"foo": 8}`,
+				"bundle/x.rego": `package system
+
+		test_fun := x {
+			x = false
+			x
+		}
+
+		undefined_test {
+			test_fun
+		}`,
+			},
+			stdIn: true,
+			input: `{"foo": 7}`,
+			assertion: func(t *testing.T, output string, err error) {
+				if err != nil {
+					t.Fatalf("unexpected error raised: %q", err.Error())
+				}
+
+				exp := `{
+  "result": [
+    {
+      "path": "--stdin-input",
+      "error": {
+        "code": "opa_undefined_error",
+        "message": "/system/main decision was undefined"
+      }
+    },
+    {
+      "path": "%ROOT%/files/test.json",
+      "error": {
+        "code": "opa_undefined_error",
+        "message": "/system/main decision was undefined"
+      }
+    }
+  ]
+}
+`
+				if output != exp {
+					t.Fatalf("expected output to be:\n\n%s\n\ngot:\n\n%s", exp, output)
+				}
+			},
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.description, func(t *testing.T) {
@@ -175,11 +221,12 @@ func TestExec(t *testing.T) {
 						os.Remove(tempFile.Name())
 					}()
 					os.Stdin = tempFile
-				} else {
-					if _, ok := tt.files["files/test.json"]; ok {
-						params.Paths = append(params.Paths, dir+"/files/")
-					}
 				}
+
+				if _, ok := tt.files["files/test.json"]; ok {
+					params.Paths = append(params.Paths, dir+"/files/")
+				}
+
 				ctx := context.Background()
 				opa, _ := sdk.New(ctx, sdk.Options{
 					Config:        bytes.NewReader([]byte{}),
@@ -190,7 +237,8 @@ func TestExec(t *testing.T) {
 				})
 
 				err := Exec(ctx, opa, params)
-				tt.assertion(err)
+				output := strings.Replace(buf.String(), dir, "%ROOT%", -1)
+				tt.assertion(t, output, err)
 			})
 		})
 	}