diff --git a/tapiro/core/src/main/scala/io/buildo/tapiro/Meta.scala b/tapiro/core/src/main/scala/io/buildo/tapiro/Meta.scala
index d5ce5340..30e1c629 100644
--- a/tapiro/core/src/main/scala/io/buildo/tapiro/Meta.scala
+++ b/tapiro/core/src/main/scala/io/buildo/tapiro/Meta.scala
@@ -1,6 +1,6 @@
 package io.buildo.tapiro
 
-import io.buildo.metarpheus.core.intermediate.{TaggedUnion, Type => MetarpheusType}
+import io.buildo.metarpheus.core.intermediate.{TaggedUnion, RouteParam, Type => MetarpheusType}
 
 import scala.meta._
 import scala.meta.contrib._
@@ -20,20 +20,20 @@ object Meta {
       val inputImplicits =
         route.method match {
           case RouteMethod.GET =>
-            nonAuthParamTypes.map(toScalametaType).map(toPlainCodec)
+            nonAuthParamTypes.map(metarpheusTypeToScalametaType).map(toPlainCodec)
           case RouteMethod.POST =>
-            nonAuthParamTypes.map(toScalametaType).flatMap(t => List(toDecoder(t), toEncoder(t)))
+            nonAuthParamTypes.map(metarpheusTypeToScalametaType).flatMap(t => List(toDecoder(t), toEncoder(t)))
         }
       val outputImplicits =
-        List(route.route.returns).filter(notUnit).map(toScalametaType).map(toJsonCodec)
+        List(route.route.returns).filter(notUnit).map(metarpheusTypeToScalametaType).map(toJsonCodec)
       val errorImplicits =
         route.error match {
           case RouteError.TaggedUnionError(tu) =>
             tu.values.map(taggedUnionMemberType(tu)).map(toJsonCodec)
           case RouteError.OtherError(t) =>
-            List(t).filter(notUnit).map(toScalametaType).map(toJsonCodec)
+            List(t).filter(notUnit).map(metarpheusTypeToScalametaType).map(toJsonCodec)
         }
-      val authImplicits = authParamTypes.map(toScalametaType).map(toPlainCodec)
+      val authImplicits = authParamTypes.map(metarpheusTypeToScalametaType).map(toPlainCodec)
       inputImplicits ++ outputImplicits ++ errorImplicits ++ authImplicits
     }
     deduplicate(routes.flatMap(routeRequiredImplicits)).zipWithIndex.map(toImplicitParam.tupled)
@@ -60,12 +60,17 @@ object Meta {
       case MetarpheusType.Name(name)     => name
     }
 
-  val toScalametaType: MetarpheusType => Type = {
+  val metarpheusTypeToScalametaType: MetarpheusType => Type = {
     case MetarpheusType.Apply(name, args) =>
-      Type.Apply(Type.Name(name), args.map(toScalametaType).toList)
+      Type.Apply(Type.Name(name), args.map(metarpheusTypeToScalametaType).toList)
     case MetarpheusType.Name(name) => Type.Name(name)
   }
 
+  val routeParamToScalametaType = (routeParam: RouteParam) => {
+    val t = metarpheusTypeToScalametaType(routeParam.tpe)
+    if (routeParam.required) t else t"Option[$t]"
+  }
+
   val taggedUnionMemberType = (taggedUnion: TaggedUnion) =>
     (member: TaggedUnion.Member) => {
       if (member.params.isEmpty)
diff --git a/tapiro/core/src/main/scala/io/buildo/tapiro/TapirMeta.scala b/tapiro/core/src/main/scala/io/buildo/tapiro/TapirMeta.scala
index 684e3190..30b8bdc2 100644
--- a/tapiro/core/src/main/scala/io/buildo/tapiro/TapirMeta.scala
+++ b/tapiro/core/src/main/scala/io/buildo/tapiro/TapirMeta.scala
@@ -56,10 +56,10 @@ object TapirMeta {
     q"val ${Pat.Var(Term.Name(route.route.name.tail.mkString))}: ${endpointType(route)} = ${endpointImpl(route)}"
 
   private[this] val endpointType = (route: TapiroRoute) => {
-    val returnType = toScalametaType(route.route.returns)
+    val returnType = metarpheusTypeToScalametaType(route.route.returns)
     val argsType = route.method match {
       case RouteMethod.GET =>
-        val argsList = route.route.params.map(p => toScalametaType(p.tpe))
+        val argsList = route.route.params.map(routeParamToScalametaType)
         argsList match {
           case Nil         => Type.Name("Unit")
           case head :: Nil => head
@@ -68,7 +68,7 @@ object TapirMeta {
       case RouteMethod.POST =>
         val authTokenType = route.route.params
           .filter(_.tpe == MetarpheusType.Name(authTokenName))
-          .map(t => toScalametaType(t.tpe))
+          .map(t => metarpheusTypeToScalametaType(t.tpe))
           .headOption
         val inputType = postInputType(route.route)
         authTokenType match {
@@ -76,7 +76,7 @@ object TapirMeta {
           case None    => inputType
         }
     }
-    val error = toScalametaType(route.error match {
+    val error = metarpheusTypeToScalametaType(route.error match {
       case RouteError.TaggedUnionError(t) => MetarpheusType.Name(t.name)
       case RouteError.OtherError(t)       => t
     })
@@ -153,7 +153,7 @@ object TapirMeta {
                 case RouteError.OtherError(MetarpheusType.Name("String")) =>
                   Term.Name("stringBody")
                 case RouteError.OtherError(t) =>
-                  Term.ApplyType(Term.Name("jsonBody"), List(toScalametaType(t)))
+                  Term.ApplyType(Term.Name("jsonBody"), List(metarpheusTypeToScalametaType(t)))
               },
             ),
           )
@@ -183,7 +183,7 @@ object TapirMeta {
           List(
             Term.ApplyType(
               Term.Name("jsonBody"),
-              List(toScalametaType(returnType)),
+              List(metarpheusTypeToScalametaType(returnType)),
             ),
           ),
         )
@@ -195,7 +195,7 @@ object TapirMeta {
         Term.Select(endpoint, Term.Name("in")),
         List(
           Term.Apply(
-            Term.ApplyType(Term.Name("query"), List(toScalametaType(param.tpe))),
+            Term.ApplyType(Term.Name("query"), List(routeParamToScalametaType(param))),
             List(Lit.String(param.name.getOrElse(typeNameString(param.tpe)))),
           ),
         ),
@@ -217,7 +217,7 @@ object TapirMeta {
         val params = route.route.params
           .filterNot(_.tpe == MetarpheusType.Name(authTokenName))
           .map { p =>
-            param"${Term.Name(p.name.getOrElse(typeNameString(p.tpe)))}: ${toScalametaType(p.tpe)}"
+            param"${Term.Name(p.name.getOrElse(typeNameString(p.tpe)))}: ${metarpheusTypeToScalametaType(p.tpe)}"
           }
         List(q"case class ${postInputType(route.route)}(..$params)")
       case RouteMethod.GET =>