diff --git a/build.sbt b/build.sbt
index 3187687ea4..355259364e 100644
--- a/build.sbt
+++ b/build.sbt
@@ -37,7 +37,8 @@ lazy val commonSettings = Seq(
     compilerPlugin("org.scalamacros" %% "paradise" % "2.1.0-M5" cross CrossVersion.full),
     compilerPlugin("org.spire-math" %% "kind-projector" % "0.6.3")
   ),
-  parallelExecution in Test := false
+  parallelExecution in Test := false,
+  scalacOptions in (Compile, doc) := (scalacOptions in (Compile, doc)).value.filter(_ != "-Xfatal-warnings")
 ) ++ warnUnusedImport
 
 lazy val commonJsSettings = Seq(
@@ -68,6 +69,7 @@ lazy val docSettings = Seq(
   ghpagesNoJekyll := false,
   siteMappings += file("CONTRIBUTING.md") -> "contributing.md",
   scalacOptions in (ScalaUnidoc, unidoc) ++= Seq(
+    "-Xfatal-warnings",
     "-doc-source-url", scmInfo.value.get.browseUrl + "/tree/master€{FILE_PATH}.scala",
     "-sourcepath", baseDirectory.in(LocalRootProject).value.getAbsolutePath,
     "-diagrams"