diff --git a/Library/Homebrew/utils/pypi.rb b/Library/Homebrew/utils/pypi.rb
index 486462be19..46a4d81402 100644
--- a/Library/Homebrew/utils/pypi.rb
+++ b/Library/Homebrew/utils/pypi.rb
@@ -27,9 +27,6 @@ module PyPI
   def update_python_resources!(formula, version = nil, print_only: false, silent: false,
                                ignore_non_pypi_packages: false)
 
-    @pipgrip_installed ||= Formula["pipgrip"].any_version_installed?
-    odie '"pipgrip" must be installed (`brew install pipgrip`)' unless @pipgrip_installed
-
     # PyPI package name isn't always the same as the formula name. Try to infer from the URL.
     pypi_name = if formula.stable.url.start_with?(PYTHONHOSTED_URL_PREFIX)
       File.basename(formula.stable.url).match(/^(.+)-[a-z\d.]+$/)[1]
@@ -52,6 +49,9 @@ module PyPI
       odie "\"#{formula.name}\" contains non-PyPI resources. Please update the resources manually."
     end
 
+    @pipgrip_installed ||= Formula["pipgrip"].any_version_installed?
+    odie '"pipgrip" must be installed (`brew install pipgrip`)' unless @pipgrip_installed
+
     ohai "Retrieving PyPI dependencies for \"#{pypi_name}==#{version}\"" if !print_only && !silent
     pipgrip_output = Utils.popen_read Formula["pipgrip"].bin/"pipgrip", "--json", "#{pypi_name}==#{version}"
     unless $CHILD_STATUS.success?