diff --git a/vortex-filtering/CMakeLists.txt b/vortex-filtering/CMakeLists.txt
index e4d12c0f..fd52b2c7 100644
--- a/vortex-filtering/CMakeLists.txt
+++ b/vortex-filtering/CMakeLists.txt
@@ -89,6 +89,7 @@ install(
 )
 
 if(BUILD_TESTING)
+  # add_compile_definitions(GNUPLOT_ENABLE=1)
   add_subdirectory(test)
 endif()
 
diff --git a/vortex-filtering/test/dynamic_model_test.cpp b/vortex-filtering/test/dynamic_model_test.cpp
index dcddc0bf..20aba047 100644
--- a/vortex-filtering/test/dynamic_model_test.cpp
+++ b/vortex-filtering/test/dynamic_model_test.cpp
@@ -51,7 +51,7 @@ TEST(DynamicModel, sampleSimpleModel)
   EXPECT_TRUE(isApproxEqual(approx_gauss.mean(), true_gauss.mean(), 0.1));
   EXPECT_TRUE(isApproxEqual(true_gauss.cov(), true_gauss.cov(), 0.1));
 
-  #ifdef GNUPLOT_ENABLE
+  #if (GNUPLOT_ENABLE)
   // Plot
   Gnuplot gp;
   gp << "set xrange [-10:10]\nset yrange [-10:10]\n";
diff --git a/vortex-filtering/test/ekf_test.cpp b/vortex-filtering/test/ekf_test.cpp
index 5cbd36fb..c9bb2e27 100644
--- a/vortex-filtering/test/ekf_test.cpp
+++ b/vortex-filtering/test/ekf_test.cpp
@@ -104,7 +104,7 @@ TEST_F(EKFTestCVModel, convergence)
   }
   time.pop_back();
 
-  #ifdef GNUPLOT_ENABLE
+  #if (GNUPLOT_ENABLE)
   Gnuplot gp;
   gp << "set terminal qt size 1600,1000\n"; // Modified to make plot larger
   gp << "set multiplot layout 2,1\n";
diff --git a/vortex-filtering/test/numerical_integration_test.cpp b/vortex-filtering/test/numerical_integration_test.cpp
index 6c07b5aa..7f738467 100644
--- a/vortex-filtering/test/numerical_integration_test.cpp
+++ b/vortex-filtering/test/numerical_integration_test.cpp
@@ -76,7 +76,7 @@ class NumericalIntegration : public ::testing::Test {
 
   void plot_result(std::string title = "ERK convergence")
   {
-    #ifdef GNUPLOT_ENABLE
+    #if (GNUPLOT_ENABLE)
     // Plot first state and true solution against time
     Gnuplot gp;
     gp << "set terminal wxt size 1200,800\n";
diff --git a/vortex-filtering/test/probability_test.cpp b/vortex-filtering/test/probability_test.cpp
index 6a1ff622..af966edd 100644
--- a/vortex-filtering/test/probability_test.cpp
+++ b/vortex-filtering/test/probability_test.cpp
@@ -94,7 +94,7 @@ TEST(MultiVarGauss, sample)
   double minorAxisLength = cov_ellipse.minor_axis();
   double angle           = cov_ellipse.angle_deg();
 
-  #ifdef GNUPLOT_ENABLE
+  #if (GNUPLOT_ENABLE)
   Gnuplot gp;
   gp << "set xrange [-10:10]\nset yrange [-10:10]\n";
   gp << "set style circle radius 0.05\n";
diff --git a/vortex-filtering/test/ukf_test.cpp b/vortex-filtering/test/ukf_test.cpp
index 7da960cf..e56f3643 100644
--- a/vortex-filtering/test/ukf_test.cpp
+++ b/vortex-filtering/test/ukf_test.cpp
@@ -108,7 +108,7 @@ TEST_F(UKFtest, Convergence)
     x_m_std.push_back(x_est.at(i).mean()(0) - std::sqrt(x_est.at(i).cov()(0, 0))); // x_est - std
   }
 
-  #ifdef GNUPLOT_ENABLE
+  #if (GNUPLOT_ENABLE)
   Gnuplot gp;
   gp << "set terminal wxt size 1200,800\n";
   gp << "set title 'UKF convergence'\n";