diff --git a/pkg/modules/api/api.go b/pkg/modules/api/api.go
index 72a831ce..3863bcac 100644
--- a/pkg/modules/api/api.go
+++ b/pkg/modules/api/api.go
@@ -462,6 +462,7 @@ func (a *Api) Start() error {
 		latencyMiddleware(),
 		rootPathMiddleware(a.rootPath),
 		traceMiddleware(a.traceHeader),
+		outputFilenameMiddleware(),
 		loggerMiddleware(a.logger, disableLoggingForPaths),
 	)
 
diff --git a/pkg/modules/api/context.go b/pkg/modules/api/context.go
index 576c3176..61c6dcb4 100644
--- a/pkg/modules/api/context.go
+++ b/pkg/modules/api/context.go
@@ -513,7 +513,7 @@ func (ctx *Context) BuildOutputFile() (string, error) {
 // OutputFilename returns the filename based on the given output path or the
 // "Gotenberg-Output-Filename" header's value.
 func (ctx *Context) OutputFilename(outputPath string) string {
-	filename := ctx.echoCtx.Request().Header.Get("Gotenberg-Output-Filename")
+	filename := ctx.echoCtx.Get("outputFilename").(string)
 
 	if filename == "" {
 		return filepath.Base(outputPath)
diff --git a/pkg/modules/api/middlewares.go b/pkg/modules/api/middlewares.go
index d1cb3c54..176d6f4d 100644
--- a/pkg/modules/api/middlewares.go
+++ b/pkg/modules/api/middlewares.go
@@ -6,6 +6,7 @@ import (
 	"errors"
 	"fmt"
 	"net/http"
+	"path/filepath"
 	"strings"
 	"time"
 
@@ -150,6 +151,25 @@ func traceMiddleware(header string) echo.MiddlewareFunc {
 	}
 }
 
+// outputFilenameMiddleware sets the output filename in the [echo.Context]
+// under "outputFilename".
+//
+//	outputFilename := c.Get("outputFilename").(string)
+func outputFilenameMiddleware() echo.MiddlewareFunc {
+	return func(next echo.HandlerFunc) echo.HandlerFunc {
+		return func(c echo.Context) error {
+			filename := c.Request().Header.Get("Gotenberg-Output-Filename")
+			// See https://github.com/gotenberg/gotenberg/issues/1227.
+			if filename != "" {
+				filename = filepath.Base(filename)
+			}
+			c.Set("outputFilename", filename)
+			// Call the next middleware in the chain.
+			return next(c)
+		}
+	}
+}
+
 // loggerMiddleware sets the logger in the [echo.Context] under "logger" and
 // logs a synchronous request result.
 //
diff --git a/test/integration/features/output_filename.feature b/test/integration/features/output_filename.feature
new file mode 100644
index 00000000..f4f8b44c
--- /dev/null
+++ b/test/integration/features/output_filename.feature
@@ -0,0 +1,33 @@
+Feature: Output Filename
+
+  Scenario: Default (Single Output File)
+    Given I have a default Gotenberg container
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/flatten" endpoint with the following form data and header(s):
+      | files                     | testdata/page_1.pdf | file   |
+      | Gotenberg-Output-Filename | foo                 | header |
+    Then the response status code should be 200
+    Then the response header "Content-Type" should be "application/pdf"
+    Then there should be the following file(s) in the response:
+      | foo.pdf |
+
+  Scenario: Default (Many Output Files)
+    Given I have a default Gotenberg container
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/flatten" endpoint with the following form data and header(s):
+      | files                     | testdata/page_1.pdf | file   |
+      | files                     | testdata/page_2.pdf | file   |
+      | Gotenberg-Output-Filename | foo                 | header |
+    Then the response status code should be 200
+    Then the response header "Content-Type" should be "application/zip"
+    Then there should be the following file(s) in the response:
+      | foo.zip |
+
+  # See https://github.com/gotenberg/gotenberg/issues/1227.
+  Scenario: Path As Filename
+    Given I have a default Gotenberg container
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/flatten" endpoint with the following form data and header(s):
+      | files                     | testdata/page_1.pdf | file   |
+      | Gotenberg-Output-Filename | /tmp/foo            | header |
+    Then the response status code should be 200
+    Then the response header "Content-Type" should be "application/pdf"
+    Then there should be the following file(s) in the response:
+      | foo.pdf |