diff --git a/bundler/lib/dependabot/bundler/file_updater/gemspec_sanitizer.rb b/bundler/lib/dependabot/bundler/file_updater/gemspec_sanitizer.rb
index bb9a6915a8..5852247421 100644
--- a/bundler/lib/dependabot/bundler/file_updater/gemspec_sanitizer.rb
+++ b/bundler/lib/dependabot/bundler/file_updater/gemspec_sanitizer.rb
@@ -234,11 +234,8 @@ def node_calls_find_dot_find?(node)
           def remove_unnecessary_assignments(node)
             return unless node.is_a?(Parser::AST::Node)
 
-            if unnecessary_assignment?(node) &&
-               node.children.last&.location.respond_to?(:heredoc_end)
-              range_to_remove = node.loc.expression.join(
-                node.children.last.location.heredoc_end
-              )
+            if unnecessary_assignment?(node) && node_includes_heredoc?(node)
+              range_to_remove = node.loc.expression.join(find_heredoc_end_range(node))
               return replace(range_to_remove, '"sanitized"')
             elsif unnecessary_assignment?(node)
               return replace(node.loc.expression, '"sanitized"')
@@ -249,6 +246,30 @@ def remove_unnecessary_assignments(node)
             end
           end
 
+          def node_includes_heredoc?(node)
+            find_heredoc_end_range(node)
+          end
+
+          # Performs a depth-first search for the first heredoc in the given
+          # Parser::AST::Node.
+          #
+          # Returns a Parser::Source::Range identifying the location of the end
+          #   of the heredoc, or nil if no heredoc was found.
+          def find_heredoc_end_range(node)
+            return unless node.is_a?(Parser::AST::Node)
+
+            node.children.each do |child|
+              next unless child.is_a?(Parser::AST::Node)
+
+              return child.location.heredoc_end if child.location.respond_to?(:heredoc_end)
+
+              range = find_heredoc_end_range(child)
+              return range if range
+            end
+
+            nil
+          end
+
           def unnecessary_assignment?(node)
             return false unless node.is_a?(Parser::AST::Node)
             return false unless node.children.first.is_a?(Parser::AST::Node)
diff --git a/bundler/spec/dependabot/bundler/file_updater/gemspec_sanitizer_spec.rb b/bundler/spec/dependabot/bundler/file_updater/gemspec_sanitizer_spec.rb
index 2c68420de5..6e3324b081 100644
--- a/bundler/spec/dependabot/bundler/file_updater/gemspec_sanitizer_spec.rb
+++ b/bundler/spec/dependabot/bundler/file_updater/gemspec_sanitizer_spec.rb
@@ -136,6 +136,23 @@
           )
         end
       end
+
+      context "that uses a heredoc with methods chained onto it" do
+        let(:content) do
+          %(Spec.new do |s|
+              s.version = "0.1.0"
+              s.post_install_message = <<~DESCRIPTION.strip.downcase
+                My description
+              DESCRIPTION
+            end)
+        end
+        it "removes the whole heredoc" do
+          expect(rewrite).to eq(
+            "Spec.new do |s|\n              s.version = \"0.1.0\""\
+            "\n              \"sanitized\"\n            end"
+          )
+        end
+      end
     end
 
     describe "version assignment" do