diff --git a/ducktrack/elements.py b/ducktrack/elements.py
index a6a4c1b85..9d08df03b 100644
--- a/ducktrack/elements.py
+++ b/ducktrack/elements.py
@@ -731,6 +731,8 @@ def track(self,p):
         #  both the position and the momentum are scaled,
         #  rather than only the momentum.
         if self.energy_ref_increment != 0:
+            old_px = p.px.copy()
+            old_py = p.py.copy()
             new_energy0 = p.mass0*p.gamma0 + self.energy_ref_increment
             new_p0c = sqrt(new_energy0*new_energy0-p.mass0*p.mass0)
             new_beta0 = new_p0c / new_energy0
@@ -739,10 +741,12 @@ def track(self,p):
 
             p.p0c = new_p0c
 
+            import pdb; pdb.set_trace()
+
             p.x *= geo_emit_factor
-            p.px *= geo_emit_factor
+            p.px = old_px * geo_emit_factor
             p.y *= geo_emit_factor
-            p.py *= geo_emit_factor
+            p.py = old_py * geo_emit_factor
 
         if self.damping_rate_x < 0.0 or self.damping_rate_y < 0.0 or self.damping_rate_s < 0.0:
             raise ValueError("Damping rates cannot be negative")
diff --git a/xtrack/beam_elements/elements_src/linesegmentmap.h b/xtrack/beam_elements/elements_src/linesegmentmap.h
index 99fc0d612..1da6d0525 100644
--- a/xtrack/beam_elements/elements_src/linesegmentmap.h
+++ b/xtrack/beam_elements/elements_src/linesegmentmap.h
@@ -304,6 +304,8 @@ void energy_and_reference_increments(LocalParticle *part0,
         // both the position and the momentum are scaled,
         // rather than only the momentum.
         if (energy_ref_increment != 0){
+            printf("px = %e\n", LocalParticle_get_px(part));
+            printf("py = %e\n", LocalParticle_get_py(part));
             double const old_px = LocalParticle_get_px(part);
             double const old_py = LocalParticle_get_py(part);
             double const new_energy0 = LocalParticle_get_mass0(part)
@@ -319,6 +321,9 @@ void energy_and_reference_increments(LocalParticle *part0,
             LocalParticle_set_py(part, old_py * geo_emit_factor);
             LocalParticle_scale_x(part, geo_emit_factor);
             LocalParticle_scale_y(part, geo_emit_factor);
+            printf("geo emit factor = %e\n", geo_emit_factor);
+            printf("px = %e\n", LocalParticle_get_px(part));
+            printf("py = %e\n", LocalParticle_get_py(part));
         }
     //end_per_particle_block