diff --git a/Source/Diagnostics/ReducedDiags/BeamRelevant.cpp b/Source/Diagnostics/ReducedDiags/BeamRelevant.cpp
index 8b244c69f0a..3911bbd936a 100644
--- a/Source/Diagnostics/ReducedDiags/BeamRelevant.cpp
+++ b/Source/Diagnostics/ReducedDiags/BeamRelevant.cpp
@@ -218,7 +218,7 @@ void BeamRelevant::ComputeDiags (int step)
                 const ParticleReal p_pos1 = p.pos(1);
                 const ParticleReal p_x_mean = p_pos0*p_w;
                 const ParticleReal p_y_mean = p_pos1*p_w;
-#elif (defined WARPX_DIM_RZ)
+#elif defined(WARPX_DIM_RZ)
                 const ParticleReal p_theta = p.rdata(PIdx::theta);
                 const ParticleReal p_x_mean = p_pos0*std::cos(p_theta)*p_w;
                 const ParticleReal p_y_mean = p_pos0*std::sin(p_theta)*p_w;