diff --git a/dist/platforms/ubuntu/run_tests.sh b/dist/platforms/ubuntu/run_tests.sh
index a4b6c57..007d9bb 100755
--- a/dist/platforms/ubuntu/run_tests.sh
+++ b/dist/platforms/ubuntu/run_tests.sh
@@ -53,6 +53,11 @@ if [ -n "$PRIVATE_REGISTRY_TOKEN" ]; then
   token = "$PRIVATE_REGISTRY_TOKEN"
   alwaysAuth = true
 EOF
+  if [ -n "$PRIVATE_REGISTRY_USER" ]; then
+    cat >> "$UPM_CONFIG_TOML_PATH" <<EOF
+  user = "$PRIVATE_REGISTRY_USER"
+EOF
+  fi
 fi
 
 #
diff --git a/src/model/image-environment-factory.ts b/src/model/image-environment-factory.ts
index 2d8450e..5babd4c 100644
--- a/src/model/image-environment-factory.ts
+++ b/src/model/image-environment-factory.ts
@@ -41,6 +41,7 @@ class ImageEnvironmentFactory {
       { name: 'SCOPED_REGISTRY_URL', value: parameters.scopedRegistryUrl },
       { name: 'REGISTRY_SCOPES', value: parameters.registryScopes },
       { name: 'PRIVATE_REGISTRY_TOKEN', value: process.env.UPM_REGISTRY_TOKEN },
+      { name: 'PRIVATE_REGISTRY_USER', value: process.env.UPM_REGISTRY_USER },
       { name: 'GIT_PRIVATE_TOKEN', value: parameters.gitPrivateToken },
       { name: 'VERSION', value: parameters.buildVersion },
       { name: 'CUSTOM_PARAMETERS', value: parameters.customParameters },