diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0e4064fd1..3ada69624 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -91,6 +91,7 @@ BUG FIXES:
       `which` since that doesn't exist on some systems. [GH-5170]
   - provisioners/chef-zero: support more chef-zero/local mode attributes [GH-5339]
   - provisioners/docker: use docker.com instead of docker.io [GH-5216]
+  - provisioners/file: validation of source is relative to Vagrantfile [GH-5252]
   - pushes/atlas: send additional box metadata [GH-5283]
   - pushes/ftp: improve check for remote directory existence [GH-5549]
   - synced\_folders/rsync: add `IdentitiesOnly=yes` to the rsync command. [GH-5175]
diff --git a/plugins/provisioners/file/config.rb b/plugins/provisioners/file/config.rb
index 2af27e67b..e8e2d6c92 100644
--- a/plugins/provisioners/file/config.rb
+++ b/plugins/provisioners/file/config.rb
@@ -1,3 +1,5 @@
+require "pathname"
+
 require "vagrant"
 
 module VagrantPlugins
@@ -15,10 +17,10 @@ module VagrantPlugins
           errors << I18n.t("vagrant.provisioners.file.no_dest_file")
         end
         if source
-          s = File.expand_path(source)
-          if ! File.exist?(s)
+          s = Pathname.new(source).expand_path(machine.env.root_path)
+          if !s.exist?
             errors << I18n.t("vagrant.provisioners.file.path_invalid",
-                              path: s)
+                              path: s.to_s)
           end
         end
 
diff --git a/test/unit/plugins/provisioners/file/config_test.rb b/test/unit/plugins/provisioners/file/config_test.rb
index e41cac966..4302a0a9c 100644
--- a/test/unit/plugins/provisioners/file/config_test.rb
+++ b/test/unit/plugins/provisioners/file/config_test.rb
@@ -7,7 +7,13 @@ describe VagrantPlugins::FileUpload::Config do
 
   subject { described_class.new }
 
-  let(:machine) { double("machine") }
+  let(:env) do
+    iso_env = isolated_environment
+    iso_env.vagrantfile("")
+    iso_env.create_vagrant_env
+  end
+
+  let(:machine) { double("machine", env: env) }
 
   describe "#validate" do
     it "returns an error if destination is not specified" do
@@ -33,7 +39,7 @@ describe VagrantPlugins::FileUpload::Config do
     end
 
     it "returns an error if source file does not exist" do
-      non_existing_file = "this/does/not/exist"
+      non_existing_file = "/this/does/not/exist"
 
       subject.source = non_existing_file
       subject.destination = "/tmp/foo"
@@ -58,7 +64,10 @@ describe VagrantPlugins::FileUpload::Config do
     end
 
     it "passes with relative source path" do
-      existing_relative_path = __FILE__
+      path = env.root_path.join("foo")
+      path.open("w+") { |f| f.write("hello") }
+
+      existing_relative_path = "foo"
 
       subject.source = existing_relative_path
       subject.destination = "/tmp/foo"