diff --git a/lib/appsignal/transaction.rb b/lib/appsignal/transaction.rb
index a42997284..cefcb79e8 100644
--- a/lib/appsignal/transaction.rb
+++ b/lib/appsignal/transaction.rb
@@ -76,18 +76,6 @@ def clear_current_transaction!
     attr_reader :ext, :transaction_id, :action, :namespace, :request, :paused, :tags, :options,
       :discarded, :breadcrumbs
 
-    # @!attribute params
-    #   Attribute for parameters of the transaction.
-    #
-    #   When no parameters are set with {#params=} the parameters it will look
-    #   for parameters on the {#request} environment.
-    #
-    #   The parameters set using {#params=} are leading over those extracted
-    #   from a request's environment.
-    #
-    #   @return [Hash]
-    attr_writer :params
-
     def initialize(transaction_id, namespace, request, options = {})
       @transaction_id = transaction_id
       @action = nil
@@ -156,6 +144,40 @@ def params
       request_params
     end
 
+    # Set parameters on the transaction.
+    #
+    # When no parameters are set this way, the transaction will look for
+    # parameters on the {#request} environment.
+    #
+    # The parameters set using {#set_params} are leading over those extracted
+    # from a request's environment.
+    #
+    # @param given_params [Hash] The parameters to set on the transaction.
+    # @return [void]
+    def set_params(given_params)
+      @params = given_params if given_params
+    end
+
+    # @deprecated Use {#set_params} or {#set_params_if_nil} instead.
+    def params=(given_params)
+      Appsignal::Utils::StdoutAndLoggerMessage.warning(
+        "Transaction#params= is deprecated." \
+          "Use Transaction#set_params or #set_params_if_nil instead."
+      )
+      set_params(given_params)
+    end
+
+    # Set parameters on the transaction if not already set
+    #
+    # When no parameters are set this way, the transaction will look for
+    # parameters on the {#request} environment.
+    #
+    # @param given_params [Hash] The parameters to set on the transaction if none are already set.
+    # @return [void]
+    def set_params_if_nil(given_params)
+      set_params(given_params) unless @params
+    end
+
     # Set tags on the transaction.
     #
     # @param given_tags [Hash] Collection of tags.
diff --git a/spec/lib/appsignal/transaction_spec.rb b/spec/lib/appsignal/transaction_spec.rb
index 7cd41165c..c1b76f1b4 100644
--- a/spec/lib/appsignal/transaction_spec.rb
+++ b/spec/lib/appsignal/transaction_spec.rb
@@ -348,9 +348,94 @@ def current_transaction
     end
 
     describe "#params=" do
+      around { |example| keep_transactions { example.run } }
+
       it "sets params on the transaction" do
-        transaction.params = { :foo => "bar" }
-        expect(transaction.params).to eq(:foo => "bar")
+        params = { "foo" => "bar" }
+        transaction.params = params
+
+        transaction.complete # Sample the data
+        expect(transaction.params).to eq(params)
+        expect(transaction.to_h.dig("sample_data", "params")).to eq(params)
+      end
+
+      it "logs a deprecation warning" do
+        transaction.params = { "foo" => "bar" }
+
+        expect(log_contents(log)).to contains_log(
+          :warn,
+          "Transaction#params= is deprecated." \
+            "Use Transaction#set_params or #set_params_if_nil instead."
+        )
+      end
+    end
+
+    describe "#set_params" do
+      around { |example| keep_transactions { example.run } }
+
+      context "when the params are set" do
+        it "updates the params on the transaction" do
+          params = { "key" => "value" }
+          transaction.set_params(params)
+
+          transaction.complete # Sample the data
+          expect(transaction.params).to eq(params)
+          expect(transaction.to_h.dig("sample_data", "params")).to eq(params)
+        end
+      end
+
+      context "when the given params is nil" do
+        it "does not update the params on the transaction" do
+          params = { "key" => "value" }
+          transaction.set_params(params)
+          transaction.set_params(nil)
+
+          transaction.complete # Sample the data
+          expect(transaction.params).to eq(params)
+          expect(transaction.to_h.dig("sample_data", "params")).to eq(params)
+        end
+      end
+    end
+
+    describe "#set_params_if_nil" do
+      around { |example| keep_transactions { example.run } }
+
+      context "when the params are not set" do
+        it "sets the params on the transaction" do
+          expect(transaction.params).to be_nil
+
+          params = { "key" => "value" }
+          transaction.set_params_if_nil(params)
+
+          transaction.complete # Sample the data
+          expect(transaction.params).to eq(params)
+          expect(transaction.to_h.dig("sample_data", "params")).to eq(params)
+        end
+
+        context "when the given params is nil" do
+          it "does not update the params on the transaction" do
+            params = { "key" => "value" }
+            transaction.set_params(params)
+            transaction.set_params_if_nil(nil)
+
+            transaction.complete # Sample the data
+            expect(transaction.params).to eq(params)
+            expect(transaction.to_h.dig("sample_data", "params")).to eq(params)
+          end
+        end
+      end
+
+      context "when the params are set" do
+        it "does not update the params on the transaction" do
+          preset_params = { "other" => "params" }
+          params = { "key" => "value" }
+          transaction.set_params(preset_params)
+          transaction.set_params_if_nil(params)
+
+          transaction.complete # Sample the data
+          expect(transaction.params).to eq(preset_params)
+          expect(transaction.to_h.dig("sample_data", "params")).to eq(preset_params)
+        end
       end
     end