diff --git a/akka-docs/src/main/paradox/stream/operators/index.md b/akka-docs/src/main/paradox/stream/operators/index.md
index 79721ca8c6..d7a4e8b970 100644
--- a/akka-docs/src/main/paradox/stream/operators/index.md
+++ b/akka-docs/src/main/paradox/stream/operators/index.md
@@ -101,8 +101,8 @@ For example, following snippet will fall with timeout exception:
 ```scala
 ...
 .toMat(StreamConverters.asInputStream().mapMaterializedValue { inputStream =>
-  inputStream.read()  // this could block forever
-  ...
+        inputStream.read()  // this could block forever
+        ...
 }).run()
 ```
 
@@ -514,6 +514,7 @@ For more background see the @ref[Error Handling in Streams](../stream-error.md)
 * [orElse](Source-or-Flow/orElse.md)
 * [Partition](Partition.md)
 * [prefixAndTail](Source-or-Flow/prefixAndTail.md)
+* [preMaterialize](Source-or-Flow/preMaterialize.md)
 * [preMaterialize](Sink/preMaterialize.md)
 * [prepend](Source-or-Flow/prepend.md)
 * [prependLazy](Source-or-Flow/prependLazy.md)
diff --git a/project/StreamOperatorsIndexGenerator.scala b/project/StreamOperatorsIndexGenerator.scala
index dbe894c2b0..ae90f1ea50 100644
--- a/project/StreamOperatorsIndexGenerator.scala
+++ b/project/StreamOperatorsIndexGenerator.scala
@@ -248,9 +248,15 @@ object StreamOperatorsIndexGenerator extends AutoPlugin {
         s"There must be at least 5 lines in $file, including the title, description, category link and an empty line between each two of them")
       // This forces the short description to be on a single line. We could make this smarter,
       // but 'forcing' the short description to be really short seems nice as well.
-      val description = lines(2)
-        .replaceAll("ref:?\\[(.*?)\\]\\(", "ref[$1](" + file.getAbsolutePath.replaceFirst(".*/([^/]+/).*", "$1"))
-      require(!description.isEmpty, s"description in $file must be non-empty, single-line description at the 3rd line")
+      val separator = java.io.File.separatorChar
+      val path =
+        if (separator != '/')
+          file.getAbsolutePath.replace(separator, '/')
+        else
+          file.getAbsolutePath
+      val description =
+        lines(2).replaceAll("ref:?\\[(.*?)\\]\\(", "ref[$1](" + path.replaceFirst(".*/([^/]+/).*", "$1"))
+      require(description.nonEmpty, s"description in $file must be non-empty, single-line description at the 3rd line")
       val categoryLink = lines(4)
       require(
         categoryLink.startsWith("@ref"),