diff --git a/src/Paket.Core/FindReferences.fs b/src/Paket.Core/FindReferences.fs
index febcc40353..c5463cf72c 100644
--- a/src/Paket.Core/FindReferences.fs
+++ b/src/Paket.Core/FindReferences.fs
@@ -6,25 +6,43 @@ open Logging
 open Paket.Domain
 open Paket.Rop
 
-let FindReferencesForPackage (dependenciesFileName, package:PackageName) =
-    let root = Path.GetDirectoryName dependenciesFileName
-    let projectFiles = ProjectFile.FindAllProjects root
-    let lockFile = LockFile.LoadFrom((DependenciesFile.FindLockfile dependenciesFileName).FullName)
-
-    [for project,referencesFile in InstallProcess.findAllReferencesFiles root |> returnOrFail do
-        let installedPackages = 
-            referencesFile
-            |> lockFile.GetPackageHull
-            |> Seq.map NormalizedPackageName
-            |> Set.ofSeq
-
-        if installedPackages.Contains(NormalizedPackageName package) then
-            yield project.FileName ]
-
-let ShowReferencesFor (dependenciesFileName, packages : PackageName list) =
-    packages
-    |> Seq.map (fun package -> package,FindReferencesForPackage(dependenciesFileName,package))
+let private findReferencesFor package (lockFile: LockFile) projects = rop {
+    let! referencedIn =
+        projects
+        |> Seq.map (fun (project, referencesFile) -> rop {
+            let! installedPackages =
+                referencesFile
+                |> lockFile.GetPackageHullSafe
+
+            let referenced =
+                installedPackages
+                |> Set.map NormalizedPackageName
+                |> Set.contains (NormalizedPackageName package)
+
+            return if referenced then Some project.FileName else None })
+        |> Rop.collect
+
+    return referencedIn |> List.choose id
+}
+
+let FindReferencesForPackage package environment = rop {
+    let! lockFile = environment |> PaketEnv.ensureLockFileExists
+
+    return! findReferencesFor package lockFile environment.Projects
+}
+
+let ShowReferencesFor packages environment = rop {
+    let! lockFile = environment |> PaketEnv.ensureLockFileExists
+    let! projectsPerPackage =
+        packages
+        |> Seq.map (fun package -> rop {
+            let! projects = findReferencesFor package lockFile environment.Projects
+            return package, projects })
+        |> Rop.collect
+
+    projectsPerPackage
     |> Seq.iter (fun (PackageName k, vs) ->
         tracefn "%s" k
-        vs |> Seq.iter (tracefn "%s")        
-        tracefn "")
\ No newline at end of file
+        vs |> Seq.iter (tracefn "%s")
+        tracefn "")
+}
\ No newline at end of file
diff --git a/src/Paket.Core/LockFile.fs b/src/Paket.Core/LockFile.fs
index 85a1d08637..e966682bef 100644
--- a/src/Paket.Core/LockFile.fs
+++ b/src/Paket.Core/LockFile.fs
@@ -284,6 +284,27 @@ module LockFileParser =
 /// Allows to parse and analyze paket.lock files.
 type LockFile(fileName:string,options,resolution:PackageResolution,remoteFiles:ResolvedSourceFile list) =
 
+    let dependenciesByPackageLazy = lazy (
+        let allDependenciesOf package =
+            let usedPackages = HashSet<_>()
+
+            let rec addPackage packageName =
+                let identity = NormalizedPackageName packageName
+                match resolution.TryFind identity with
+                | Some package ->
+                    if usedPackages.Add packageName then
+                        if not options.Strict then
+                            for d,_,_ in package.Dependencies do
+                                addPackage d
+                | None -> ()
+
+            addPackage package
+
+            usedPackages
+
+        resolution
+        |> Map.map (fun _ package -> allDependenciesOf package.Name))
+
     member __.SourceFiles = remoteFiles
     member __.ResolvedPackages = resolution
     member __.FileName = fileName
@@ -308,24 +329,17 @@ type LockFile(fileName:string,options,resolution:PackageResolution,remoteFiles:R
         usedPackages
 
     /// Gets all dependencies of the given package
-    member this.GetAllDependenciesOf(package) = 
-        let usedPackages = HashSet<_>()
-
-        let rec addPackage (packageName:PackageName) =
-            let identity = NormalizedPackageName packageName
-            match resolution.TryFind identity with
-            | Some package ->
-                if usedPackages.Add packageName then
-                    if not this.Options.Strict then
-                        for d,_,_ in package.Dependencies do
-                            addPackage d
-            | None ->
-                let (PackageName name) = packageName
-                failwithf "Package %s was referenced, but it was not found in the paket.lock file." name
-
-        addPackage package
+    member this.GetAllDependenciesOf(package) =
+        match this.GetAllDependenciesOfSafe package with
+        | Some packages -> packages
+        | None ->
+            let (PackageName name) = package
+            failwithf "Package %s was referenced, but it was not found in the paket.lock file." name
 
-        usedPackages
+    /// Gets all dependencies of the given package
+    member this.GetAllDependenciesOfSafe(package) =
+        dependenciesByPackageLazy.Value
+        |> Map.tryFind (NormalizedPackageName package)
 
     member this.GetAllNormalizedDependenciesOf(package:PackageName) = 
         this.GetAllDependenciesOf(package)
@@ -396,3 +410,11 @@ type LockFile(fileName:string,options,resolution:PackageResolution,remoteFiles:R
             with exn -> failwithf "%s - in %s" exn.Message referencesFile.FileName)
 
         usedPackages   
+
+    member this.GetPackageHullSafe referencesFile =
+        referencesFile.NugetPackages
+        |> Seq.map (fun package ->
+            this.GetAllDependenciesOfSafe(package)
+            |> Rop.failIfNone (ReferenceNotFoundInLockFile(referencesFile.FileName, package)))
+        |> Rop.collect
+        |> Rop.lift (Seq.concat >> Set.ofSeq)
diff --git a/src/Paket.Core/PublicAPI.fs b/src/Paket.Core/PublicAPI.fs
index ee7195936e..ed9aea8100 100644
--- a/src/Paket.Core/PublicAPI.fs
+++ b/src/Paket.Core/PublicAPI.fs
@@ -94,6 +94,16 @@ type Dependencies(dependenciesFileName: string) =
     /// Get the root path
     member this.RootPath with get() = Path.GetDirectoryName(dependenciesFileName)
 
+    /// Get the root directory
+    member private this.RootDirectory with get() = DirectoryInfo(this.RootPath)
+
+    /// Binds the given processing ROP function to current environment and executes it.
+    /// Throws on failure.
+    member private this.Process f =
+        PaketEnv.fromRootDirectory(this.RootDirectory)
+        >>= f
+        |> returnOrFail
+
     /// Adds the given package without version requirements to the dependencies file.
     member this.Add(package: string): unit = this.Add(package,"")
 
@@ -199,8 +209,8 @@ type Dependencies(dependenciesFileName: string) =
 
     /// Shows all references for the given packages.
     member this.ShowReferencesFor(packages: string list): unit =
-        FindReferences.ShowReferencesFor(dependenciesFileName,packages |> List.map PackageName)
+        FindReferences.ShowReferencesFor (packages |> List.map PackageName) |> this.Process
 
     /// Finds all references for a given package.
     member this.FindReferencesFor(package: string): string list =
-        FindReferences.FindReferencesForPackage(dependenciesFileName, PackageName package)
+        FindReferences.FindReferencesForPackage (PackageName package) |> this.Process
diff --git a/src/Paket.Core/Rop.fs b/src/Paket.Core/Rop.fs
index aca19facdb..eec44e12f9 100644
--- a/src/Paket.Core/Rop.fs
+++ b/src/Paket.Core/Rop.fs
@@ -87,6 +87,7 @@ let (<!>) = lift
 let (<*>) = apply
 
 type RopBuilder() =
+    member __.Zero() = succeed ()
     member __.Bind(m, f) = bind f m
     member __.Return(x) = succeed x
     member __.ReturnFrom(x) = x