diff --git a/scalafix/build.sbt b/scalafix/build.sbt
index f091f184..5cf2d509 100644
--- a/scalafix/build.sbt
+++ b/scalafix/build.sbt
@@ -37,7 +37,8 @@ lazy val tests = project
         sourceDirectory.in(output, Compile).value,
       "inputClassdirectory" ->
         classDirectory.in(input, Compile).value
-    )
+    ),
+    test in Test := (test in Test).dependsOn(compile in (output, Compile)).value
   )
   .dependsOn(input, rules)
   .enablePlugins(BuildInfoPlugin)
diff --git a/scalafix/input/src/main/scala/fix/RetainSrc.scala b/scalafix/input/src/main/scala/fix/RetainSrc.scala
new file mode 100644
index 00000000..2ba1ca6c
--- /dev/null
+++ b/scalafix/input/src/main/scala/fix/RetainSrc.scala
@@ -0,0 +1,11 @@
+/*
+rule = "scala:fix.Scalacollectioncompat_NewCollections"
+ */
+package fix
+
+import scala.collection.mutable.Map
+
+class MethodRenames(xs: Map[Int, Int]) {
+  xs.retain((_, _) => true)
+  xs.retain{case (x, y) => true}
+}
\ No newline at end of file
diff --git a/scalafix/output/src/main/scala/fix/RetainSrc.scala b/scalafix/output/src/main/scala/fix/RetainSrc.scala
new file mode 100644
index 00000000..950570c6
--- /dev/null
+++ b/scalafix/output/src/main/scala/fix/RetainSrc.scala
@@ -0,0 +1,8 @@
+package fix
+
+import scala.collection.mutable.Map
+
+class MethodRenames(xs: Map[Int, Int]) {
+  xs.filterInPlace{case (_, _) => true}
+  xs.filterInPlace{case (x, y) => true}
+}
\ No newline at end of file
diff --git a/scalafix/project/plugins.sbt b/scalafix/project/plugins.sbt
index b23cfd7c..0fd7a907 100644
--- a/scalafix/project/plugins.sbt
+++ b/scalafix/project/plugins.sbt
@@ -1,3 +1,3 @@
-addSbtPlugin("ch.epfl.scala" % "sbt-scalafix" % "0.5.7")
+addSbtPlugin("ch.epfl.scala" % "sbt-scalafix" % "0.5.10")
 addSbtPlugin("io.get-coursier" % "sbt-coursier" % "1.0.0")
 addSbtPlugin("com.eed3si9n" % "sbt-buildinfo" % "0.6.1")
\ No newline at end of file
diff --git a/scalafix/rules/src/main/scala/fix/Scalacollectioncompat_NewCollections.scala b/scalafix/rules/src/main/scala/fix/Scalacollectioncompat_NewCollections.scala
index 7d2cc087..8f660cb8 100644
--- a/scalafix/rules/src/main/scala/fix/Scalacollectioncompat_NewCollections.scala
+++ b/scalafix/rules/src/main/scala/fix/Scalacollectioncompat_NewCollections.scala
@@ -30,6 +30,28 @@ case class Scalacollectioncompat_NewCollections(index: SemanticdbIndex)
     Symbol("_root_.scala.runtime.Tuple3Zipped.Ops.zipped.")
   )
 
+  val retain = 
+    SymbolMatcher.normalized(
+      Symbol("_root_.scala.collection.mutable.MapLike.retain.")
+    )
+
+  def replaceMutableMap(ctx: RuleCtx) =
+    ctx.tree.collect {
+      case Term.Apply(Term.Select(_, retain(n: Name)), List(_: Term.PartialFunction)) =>
+        ctx.replaceTree(n, "filterInPlace")
+
+      case Term.Apply(Term.Select(_, retain(n: Name)), List(_: Term.Function)) =>
+        (for {
+          name <- n.tokens.lastOption
+          open <- ctx.tokenList.find(name)(t => t.is[Token.LeftParen])
+          close <- ctx.matchingParens.close(open.asInstanceOf[Token.LeftParen])
+        } yield
+          ctx.replaceToken(open, "{case ") +
+          ctx.replaceToken(close, "}") +
+          ctx.replaceTree(n, "filterInPlace")  
+        ).asPatch   
+    }.asPatch
+
   def replaceToList(ctx: RuleCtx) =
     ctx.tree.collect {
       case iterator(t: Name) =>
@@ -110,6 +132,7 @@ case class Scalacollectioncompat_NewCollections(index: SemanticdbIndex)
       replaceSymbols(ctx) +
       replaceTupleZipped(ctx) +
       replaceCopyToBuffer(ctx) +
-      replaceStreamAppend(ctx)
+      replaceStreamAppend(ctx) +
+      replaceMutableMap(ctx)
   }
 }