diff --git a/modules/lm-coursier/src/main/scala/lmcoursier/internal/ResolutionParams.scala b/modules/lm-coursier/src/main/scala/lmcoursier/internal/ResolutionParams.scala
index 7eb896dc1..2dd3299c2 100644
--- a/modules/lm-coursier/src/main/scala/lmcoursier/internal/ResolutionParams.scala
+++ b/modules/lm-coursier/src/main/scala/lmcoursier/internal/ResolutionParams.scala
@@ -38,7 +38,7 @@ final case class ResolutionParams(
         .toMap
 
       Seq(
-        InMemoryRepository(map)
+        TemporaryInMemoryRepository(map, cache)
       )
     }
 
diff --git a/modules/lm-coursier/src/main/scala/lmcoursier/internal/TemporaryInMemoryRepository.scala b/modules/lm-coursier/src/main/scala/lmcoursier/internal/TemporaryInMemoryRepository.scala
new file mode 100644
index 000000000..7bf2721bc
--- /dev/null
+++ b/modules/lm-coursier/src/main/scala/lmcoursier/internal/TemporaryInMemoryRepository.scala
@@ -0,0 +1,216 @@
+package lmcoursier.internal
+
+import java.io.{File, FileNotFoundException, IOException}
+import java.net.{HttpURLConnection, URL, URLConnection}
+
+import coursier.cache.{CacheUrl, FileCache}
+import coursier.core._
+import coursier.util.{EitherT, Monad}
+
+import scala.util.Try
+
+object TemporaryInMemoryRepository {
+
+  def closeConn(conn: URLConnection): Unit = {
+    Try(conn.getInputStream).toOption.filter(_ != null).foreach(_.close())
+    conn match {
+      case conn0: HttpURLConnection =>
+        Try(conn0.getErrorStream).toOption.filter(_ != null).foreach(_.close())
+        conn0.disconnect()
+      case _ =>
+    }
+  }
+
+  def exists(
+    url: URL,
+    localArtifactsShouldBeCached: Boolean
+  ): Boolean =
+    exists(url, localArtifactsShouldBeCached, None)
+
+  def exists(
+    url: URL,
+    localArtifactsShouldBeCached: Boolean,
+    cacheOpt: Option[FileCache[Nothing]]
+  ): Boolean = {
+
+    // Sometimes HEAD attempts fail even though standard GETs are fine.
+    // E.g. https://github.com/NetLogo/NetLogo/releases/download/5.3.1/NetLogo.jar
+    // returning 403s. Hence the second attempt below.
+
+    val protocolSpecificAttemptOpt = {
+
+      def ifFile: Option[Boolean] = {
+        if (localArtifactsShouldBeCached && !new File(url.toURI).exists()) {
+          val cachePath = coursier.cache.CacheDefaults.location
+          // 'file' here stands for the protocol (e.g. it's https instead for https:// URLs)
+          Some(new File(cachePath, s"file/${url.getPath}").exists())
+        } else {
+          Some(new File(url.toURI).exists()) // FIXME Escaping / de-escaping needed here?
+        }
+      }
+
+      def ifHttp: Option[Boolean] = {
+        // HEAD request attempt, adapted from http://stackoverflow.com/questions/22541629/android-how-can-i-make-an-http-head-request/22545275#22545275
+
+        var conn: URLConnection = null
+        try {
+          conn = CacheUrl.urlConnection(
+            url.toString,
+            None,
+            followHttpToHttpsRedirections = cacheOpt.fold(false)(_.followHttpToHttpsRedirections),
+            followHttpsToHttpRedirections = cacheOpt.fold(false)(_.followHttpsToHttpRedirections),
+            sslSocketFactoryOpt = cacheOpt.flatMap(_.sslSocketFactoryOpt),
+            hostnameVerifierOpt = cacheOpt.flatMap(_.hostnameVerifierOpt),
+            method = "HEAD",
+            maxRedirectionsOpt = cacheOpt.flatMap(_.maxRedirections)
+          )
+          // Even though the finally clause handles this too, this has to be run here, so that we return Some(true)
+          // iff this doesn't throw.
+          conn.getInputStream.close()
+          Some(true)
+        }
+        catch {
+          case _: FileNotFoundException => Some(false)
+          case _: IOException           => None // error other than not found
+        }
+        finally {
+          if (conn != null)
+            closeConn(conn)
+        }
+      }
+
+      url.getProtocol match {
+        case "file"           => ifFile
+        case "http" | "https" => ifHttp
+        case _                => None
+      }
+    }
+
+    def genericAttempt: Boolean = {
+      var conn: URLConnection = null
+      try {
+        conn = url.openConnection()
+        // NOT setting request type to HEAD here.
+        conn.getInputStream.close()
+        true
+      }
+      catch {
+        case _: IOException => false
+      }
+      finally {
+        if (conn != null)
+          closeConn(conn)
+      }
+    }
+
+    protocolSpecificAttemptOpt
+      .getOrElse(genericAttempt)
+  }
+
+  def apply(
+    fallbacks: Map[(Module, String), (URL, Boolean)]
+  ): TemporaryInMemoryRepository =
+    new TemporaryInMemoryRepository(fallbacks, localArtifactsShouldBeCached = false, None)
+
+  def apply(
+    fallbacks: Map[(Module, String), (URL, Boolean)],
+    localArtifactsShouldBeCached: Boolean
+  ): TemporaryInMemoryRepository =
+    new TemporaryInMemoryRepository(fallbacks, localArtifactsShouldBeCached, None)
+
+  def apply[F[_]](
+    fallbacks: Map[(Module, String), (URL, Boolean)],
+    cache: FileCache[F]
+  ): TemporaryInMemoryRepository =
+    new TemporaryInMemoryRepository(
+      fallbacks,
+      localArtifactsShouldBeCached = cache.localArtifactsShouldBeCached,
+      Some(cache.asInstanceOf[FileCache[Nothing]])
+    )
+
+}
+
+final class TemporaryInMemoryRepository private(
+  val fallbacks: Map[(Module, String), (URL, Boolean)],
+  val localArtifactsShouldBeCached: Boolean,
+  val cacheOpt: Option[FileCache[Nothing]]
+) extends Repository {
+
+  def find[F[_]](
+    module: Module,
+    version: String,
+    fetch: Repository.Fetch[F]
+  )(implicit
+    F: Monad[F]
+  ): EitherT[F, String, (Artifact.Source, Project)] = {
+
+    def res = fallbacks
+      .get((module, version))
+      .fold[Either[String, (Artifact.Source, Project)]](Left("No fallback URL found")) {
+        case (url, _) =>
+
+          println(s"($module, $version) -> $url")
+
+          val urlStr = url.toExternalForm
+          val idx = urlStr.lastIndexOf('/')
+
+          if (idx < 0 || urlStr.endsWith("/"))
+            Left(s"$url doesn't point to a file")
+          else {
+            val (dirUrlStr, fileName) = urlStr.splitAt(idx + 1)
+
+            if (TemporaryInMemoryRepository.exists(url, localArtifactsShouldBeCached, cacheOpt)) {
+              println("returning proj")
+              val proj = Project(
+                module,
+                version,
+                Nil,
+                Map.empty,
+                None,
+                Nil,
+                Nil,
+                Nil,
+                None,
+                None,
+                None,
+                relocated = false,
+                None,
+                Nil,
+                Info.empty
+              )
+
+              Right((this, proj))
+            } else
+              Left(s"$fileName not found under $dirUrlStr")
+          }
+      }
+
+    // EitherT(F.bind(F.point(()))(_ => F.point(res)))
+    EitherT(F.map(F.point(()))(_ => res))
+  }
+
+  def artifacts(
+    dependency: Dependency,
+    project: Project,
+    overrideClassifiers: Option[Seq[Classifier]]
+  ): Seq[(Publication, Artifact)] = {
+    println(s"artifacts($dependency)")
+    fallbacks
+      .get(dependency.moduleVersion)
+      .toSeq
+      .map {
+        case (url, changing) =>
+          println(s"$url, $changing")
+          val url0 = url.toString
+          val ext = url0.substring(url0.lastIndexOf('.') + 1)
+          val pub = Publication(
+            dependency.module.name.value, // ???
+            Type(ext),
+            Extension(ext),
+            Classifier.empty
+          )
+          (pub, Artifact(url0, Map.empty, Map.empty, changing, optional = false, None))
+      }
+  }
+
+}