diff --git a/build.sbt b/build.sbt
index 21f88cf1307..2171b02034e 100644
--- a/build.sbt
+++ b/build.sbt
@@ -1045,7 +1045,9 @@ lazy val std = crossProject(JSPlatform, JVMPlatform, NativePlatform)
         ProblemFilters.exclude[FinalMethodProblem](
           "cats.effect.std.Dispatcher#RegState#Unstarted.toString"),
         ProblemFilters.exclude[DirectMissingMethodProblem](
-          "cats.effect.std.Dispatcher#Registration#Primary.*")
+          "cats.effect.std.Dispatcher#Registration#Primary.*"),
+        // #4065, moved to its own file.
+        ProblemFilters.exclude[MissingClassProblem]("cats.effect.std.Mutex$ConcurrentImpl$")
       )
   )
   .jsSettings(