diff --git a/rfg_vna_viewer.py b/rfg_vna_viewer.py
index 8739963..4039a4a 100644
--- a/rfg_vna_viewer.py
+++ b/rfg_vna_viewer.py
@@ -136,7 +136,7 @@ def process_main(main_ch1, main_ch2, ref_amplitude, ref_phase_aligned):
 
     # Normalize by ref amplitude and subtract ref phase of first point
     ref_amp_safe = np.where(ref_amplitude > 1e-12, ref_amplitude, 1e-12)
-    z_norm = (ch1_v / ref_amp_safe + 1j * ch2_v / ref_amp_safe) * np.exp(-1j * ref_phase_aligned[0])
+    z_norm = (ch1_v / ref_amp_safe + 1j * ch2_v / ref_amp_safe) * np.exp(-1j * ref_phase_aligned)
 
     norm_ch1 = np.real(z_norm)
     norm_ch2 = np.imag(z_norm)
@@ -239,7 +239,7 @@ def build_gui():
 # ---------------------------------------------------------------------------
 def make_update(reader, parser, assembler, curves, plots):
     c_main_amp, c_ref_amp, c_norm_ch1, c_norm_ch2, c_norm_amp, c_ph, c_ph_line, c_ph_dev, c_fft = curves
-    state = {"axes_locked": False}
+    state = {"ref_phase_first": None, "axes_locked": False}
     queue = deque(maxlen=64)
 
     def update():
@@ -272,8 +272,12 @@ def make_update(reader, parser, assembler, curves, plots):
             sweep["ref_ch1"], sweep["ref_ch2"]
         )
 
+        # Fix reference phase from the first sweep
+        if state["ref_phase_first"] is None:
+            state["ref_phase_first"] = ref_phase[0]
+
         main_amp, ref_amplitude, norm_ch1, norm_ch2, norm_amp, phase, fft_mag, fft_dist = process_main(
-            sweep["main_ch1"], sweep["main_ch2"], ref_amp, ref_phase
+            sweep["main_ch1"], sweep["main_ch2"], ref_amp, state["ref_phase_first"]
         )
 
         c_main_amp.setData(freqs_ghz, main_amp)