diff --git a/openapi-codegen/core/src/main/scala/sttp/tapir/codegen/EndpointGenerator.scala b/openapi-codegen/core/src/main/scala/sttp/tapir/codegen/EndpointGenerator.scala
index 2e66241867..400ac50df6 100644
--- a/openapi-codegen/core/src/main/scala/sttp/tapir/codegen/EndpointGenerator.scala
+++ b/openapi-codegen/core/src/main/scala/sttp/tapir/codegen/EndpointGenerator.scala
@@ -382,7 +382,7 @@ class EndpointGenerator {
               case StreamingImplementation.Pekko => "sttp.capabilities.pekko.PekkoStreams"
               case StreamingImplementation.Zio   => "sttp.capabilities.zio.ZioStreams"
             }
-            s"streamTextBody($capability)(CodecFormat.TextPlain())"
+            s"streamTextBody($capability)(CodecFormat.OctetStream())"
           case x => bail(s"$contentType only supports binary schema. Found $x")
         }
 
diff --git a/openapi-codegen/sbt-plugin/src/sbt-test/sbt-openapi-codegen/oneOf-json-roundtrip/Expected.scala.txt b/openapi-codegen/sbt-plugin/src/sbt-test/sbt-openapi-codegen/oneOf-json-roundtrip/Expected.scala.txt
index 1ed8446f74..454c390615 100644
--- a/openapi-codegen/sbt-plugin/src/sbt-test/sbt-openapi-codegen/oneOf-json-roundtrip/Expected.scala.txt
+++ b/openapi-codegen/sbt-plugin/src/sbt-test/sbt-openapi-codegen/oneOf-json-roundtrip/Expected.scala.txt
@@ -123,13 +123,13 @@ object TapirGeneratedEndpoints {
     endpoint
       .get
       .in(("binary" / "test"))
-      .out(streamTextBody(sttp.capabilities.pekko.PekkoStreams)(CodecFormat.TextPlain()).description("Response CSV body"))
+      .out(streamTextBody(sttp.capabilities.pekko.PekkoStreams)(CodecFormat.OctetStream()).description("Response CSV body"))
 
   lazy val postBinaryTest =
     endpoint
       .post
       .in(("binary" / "test"))
-      .in(streamTextBody(sttp.capabilities.pekko.PekkoStreams)(CodecFormat.TextPlain()))
+      .in(streamTextBody(sttp.capabilities.pekko.PekkoStreams)(CodecFormat.OctetStream()))
       .out(jsonBody[String].description("successful operation"))
 
   lazy val putAdtTest =