diff --git a/npm_and_yarn/lib/dependabot/npm_and_yarn/file_updater/npmrc_builder.rb b/npm_and_yarn/lib/dependabot/npm_and_yarn/file_updater/npmrc_builder.rb
index 2101467e51b..7415ca6dfce 100644
--- a/npm_and_yarn/lib/dependabot/npm_and_yarn/file_updater/npmrc_builder.rb
+++ b/npm_and_yarn/lib/dependabot/npm_and_yarn/file_updater/npmrc_builder.rb
@@ -114,19 +114,19 @@ def build_npmrc_from_yarnrc
         def credential_lines_for_npmrc
           lines = []
           registry_credentials.each do |cred|
-            registry = cred.fetch("registry")
+            registry = cred.fetch("registry").sub(%r{\/?$}, "/")
 
             lines << registry_scope(registry) if registry_scope(registry)
 
             token = cred.fetch("token")
             if token.include?(":")
               encoded_token = Base64.encode64(token).delete("\n")
-              lines << "//#{registry}/:_auth=#{encoded_token}"
+              lines << "//#{registry}:_auth=#{encoded_token}"
             elsif Base64.decode64(token).ascii_only? &&
                   Base64.decode64(token).include?(":")
-              lines << %(//#{registry}/:_auth=#{token.delete("\n")})
+              lines << %(//#{registry}:_auth=#{token.delete("\n")})
             else
-              lines << "//#{registry}/:_authToken=#{token}"
+              lines << "//#{registry}:_authToken=#{token}"
             end
           end
 
@@ -163,7 +163,7 @@ def registry_scope(registry)
           # This just seems unlikely
           return unless scopes.uniq.count == 1
 
-          "@#{scopes.first}:registry=https://#{registry}/"
+          "@#{scopes.first}:registry=https://#{registry}"
         end
 
         def registry_credentials
diff --git a/npm_and_yarn/spec/dependabot/npm_and_yarn/file_updater/npmrc_builder_spec.rb b/npm_and_yarn/spec/dependabot/npm_and_yarn/file_updater/npmrc_builder_spec.rb
index 226d586ad2a..77e30183122 100644
--- a/npm_and_yarn/spec/dependabot/npm_and_yarn/file_updater/npmrc_builder_spec.rb
+++ b/npm_and_yarn/spec/dependabot/npm_and_yarn/file_updater/npmrc_builder_spec.rb
@@ -175,6 +175,28 @@
           end
           it { is_expected.to eq("//registry.npmjs.org/:_authToken=my_token") }
 
+          context "where the registry has a trailing slash" do
+            let(:credentials) do
+              [{
+                "type" => "git_source",
+                "host" => "github.com",
+                "username" => "x-access-token",
+                "password" => "token"
+              }, {
+                "type" => "npm_registry",
+                "registry" => "artifactory.jfrog.com"\
+                              "/artifactory/api/npm/dependabot/",
+                "token" => "my_token"
+              }]
+            end
+
+            it "only adds a single trailing slash" do
+              expect(npmrc_content).
+                to eq("//artifactory.jfrog.com/"\
+                      "artifactory/api/npm/dependabot/:_authToken=my_token")
+            end
+          end
+
           context "that match a scoped package" do
             let(:credentials) do
               [{