diff --git a/lib/u3d/installer.rb b/lib/u3d/installer.rb
index 2b9ef47e..9c9f03d5 100644
--- a/lib/u3d/installer.rb
+++ b/lib/u3d/installer.rb
@@ -146,9 +146,12 @@ def package_destination(info, unity_root_path)
       end
     end
 
+    # extra installation paths are stored in U3D_EXTRA_PATHS environment variable,
+    # following a standard PATH variable format.
+    # Returns an array of ruby style paths
     def extra_installation_paths
       return [] if ENV['U3D_EXTRA_PATHS'].nil?
-      ENV['U3D_EXTRA_PATHS'].strip.split(File::PATH_SEPARATOR)
+      ENV['U3D_EXTRA_PATHS'].strip.split(File::PATH_SEPARATOR).map { |p| File.expand_path p }
     end
 
     def find_installations_with_path(default_root_path: '', postfix: [])
diff --git a/spec/u3d/installer_spec.rb b/spec/u3d/installer_spec.rb
index f8e74cfe..03ed6971 100644
--- a/spec/u3d/installer_spec.rb
+++ b/spec/u3d/installer_spec.rb
@@ -88,6 +88,30 @@ class DummyInstaller < U3d::BaseInstaller
           expect(installer.installed_sorted_by_versions).to eq(sorted_installed)
         end
       end
+
+      describe ".extra_installation_paths" do
+        describe "converts paths to ruby paths" do
+          def expect_extra_installation_paths(env_var, expected_paths)
+            installer = DummyInstaller.new
+            with_env_values('U3D_EXTRA_PATHS' => env_var) do
+              expect(installer.send(:extra_installation_paths)).to eql(expected_paths)
+            end
+          end
+          it "works on Windows", if: WINDOWS do
+            expect_extra_installation_paths(
+              "C:\\Program Files\\Unity;D:\\",
+              ["C:/Program Files/Unity", "D:/"]
+            )
+          end
+
+          it "works on Unix", unless: WINDOWS do
+            expect_extra_installation_paths(
+              "/Applications/here:/Applications/else",
+              ["/Applications/here", "/Applications/else"]
+            )
+          end
+        end
+      end
     end
 
     describe U3d::MacInstaller, unless: WINDOWS do
diff --git a/spec/u3d_core/helper_spec.rb b/spec/u3d_core/helper_spec.rb
new file mode 100644
index 00000000..1ec1634a
--- /dev/null
+++ b/spec/u3d_core/helper_spec.rb
@@ -0,0 +1,33 @@
+## --- BEGIN LICENSE BLOCK ---
+# Copyright (c) 2019-present WeWantToKnow AS
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+## --- END LICENSE BLOCK ---
+
+require 'u3d/utils'
+
+describe U3dCore do
+  describe U3d::Helper do
+    describe '.windows_path' do
+      it 'converts paths' do
+        expect(U3dCore::Helper.windows_path('/path/to/file')).to eql "\\path\\to\\file"
+      end
+    end
+  end
+end