diff --git a/docs/hello-sse/api.wasm b/docs/hello-sse/api.wasm
index cfe3735..539bf07 100755
Binary files a/docs/hello-sse/api.wasm and b/docs/hello-sse/api.wasm differ
diff --git a/docs/hello-state/api.wasm b/docs/hello-state/api.wasm
index 68b9078..b5787fe 100755
Binary files a/docs/hello-state/api.wasm and b/docs/hello-state/api.wasm differ
diff --git a/docs/hello/api.wasm b/docs/hello/api.wasm
index 0efda26..3232078 100755
Binary files a/docs/hello/api.wasm and b/docs/hello/api.wasm differ
diff --git a/request.go b/request.go
index 824b0ba..5f414f6 100644
--- a/request.go
+++ b/request.go
@@ -6,6 +6,7 @@ import (
 	"net/http/httptest"
 	"syscall/js"
 
+	promise "github.com/nlepage/go-js-promise"
 	"github.com/nlepage/go-wasm-http-server/v2/internal/readablestream"
 	"github.com/nlepage/go-wasm-http-server/v2/internal/safejs"
 )
@@ -30,7 +31,26 @@ func Request(uvalue js.Value) (*http.Request, error) {
 	}
 
 	var bodyReader io.Reader
-	if !body.IsUndefined() && !body.IsNull() {
+
+	if !body.IsNull() {
+		// WORKAROUND: Firefox does not have request.body ReadableStream
+		if body.IsUndefined() {
+			blobp, err := value.Call("blob")
+			if err != nil {
+				return nil, err
+			}
+
+			blob, err := promise.Await(safejs.Unsafe(blobp))
+			if err != nil {
+				return nil, err
+			}
+
+			body, err = safejs.Safe(blob).Call("stream")
+			if err != nil {
+				return nil, err
+			}
+		}
+
 		r, err := body.Call("getReader")
 		if err != nil {
 			return nil, err
diff --git a/response.go b/response.go
index 36f46f1..07693e4 100644
--- a/response.go
+++ b/response.go
@@ -136,6 +136,7 @@ func (r *response) Context() context.Context {
 func (r *response) WriteError(str string) {
 	slog.Error(str)
 	if !r.wroteHeader {
+		r.Header().Set("Content-Type", "text/plain")
 		r.WriteHeader(500)
 		_, _ = r.WriteString(str)
 	}