diff --git a/Library/Homebrew/service.rb b/Library/Homebrew/service.rb
index 2e4aefe46b..588642960e 100644
--- a/Library/Homebrew/service.rb
+++ b/Library/Homebrew/service.rb
@@ -46,8 +46,11 @@ module Homebrew
     }
     def run(command = nil, macos: nil, linux: nil)
       # Save parameters for serialization
-      @run_params ||= command
-      @run_params ||= { macos: macos, linux: linux }.compact
+      if command
+        @run_params = command
+      elsif macos || linux
+        @run_params = { macos: macos, linux: linux }.compact
+      end
 
       command ||= on_system_conditional(macos: macos, linux: linux)
       case T.unsafe(command)
@@ -551,15 +554,22 @@ module Homebrew
       hash = {}
       hash[:run] =
         case api_hash["run"]
-        when Hash
-          api_hash["run"].to_h do |key, array|
-            [
-              key.to_sym,
-              array.map(&method(:replace_placeholders)),
-            ]
-          end
+        when String
+          replace_placeholders(api_hash["run"])
         when Array
           api_hash["run"].map(&method(:replace_placeholders))
+        when Hash
+          api_hash["run"].to_h do |key, elem|
+            run_cmd = if elem.is_a?(Array)
+              elem.map(&method(:replace_placeholders))
+            else
+              replace_placeholders(elem)
+            end
+
+            [key.to_sym, run_cmd]
+          end
+        else
+          raise ArgumentError, "Unexpected run command: #{api_hash["run"]}"
         end
 
       hash[:keep_alive] = api_hash["keep_alive"].transform_keys(&:to_sym) if api_hash.key?("keep_alive")
diff --git a/Library/Homebrew/test/service_spec.rb b/Library/Homebrew/test/service_spec.rb
index f9089f012f..35fde30940 100644
--- a/Library/Homebrew/test/service_spec.rb
+++ b/Library/Homebrew/test/service_spec.rb
@@ -975,5 +975,37 @@ describe Homebrew::Service do
     it "replaces placeholders with local paths" do
       expect(described_class.deserialize(serialized_hash)).to eq(deserialized_hash)
     end
+
+    describe "run command" do
+      it "handles String argument correctly" do
+        expect(described_class.deserialize({
+          "run" => "$HOMEBREW_PREFIX/opt/formula_name/bin/beanstalkd",
+        })).to eq({
+          run: "#{HOMEBREW_PREFIX}/opt/formula_name/bin/beanstalkd",
+        })
+      end
+
+      it "handles Array argument correctly" do
+        expect(described_class.deserialize({
+          "run" => ["$HOMEBREW_PREFIX/opt/formula_name/bin/beanstalkd", "--option"],
+        })).to eq({
+          run: ["#{HOMEBREW_PREFIX}/opt/formula_name/bin/beanstalkd", "--option"],
+        })
+      end
+
+      it "handles Hash argument correctly" do
+        expect(described_class.deserialize({
+          "run" => {
+            "linux" => "$HOMEBREW_PREFIX/opt/formula_name/bin/beanstalkd",
+            "macos" => ["$HOMEBREW_PREFIX/opt/formula_name/bin/beanstalkd", "--option"],
+          },
+        })).to eq({
+          run: {
+            linux: "#{HOMEBREW_PREFIX}/opt/formula_name/bin/beanstalkd",
+            macos: ["#{HOMEBREW_PREFIX}/opt/formula_name/bin/beanstalkd", "--option"],
+          },
+        })
+      end
+    end
   end
 end