diff --git a/sfm/compliance.py b/sfm/compliance.py
index 2b21585..bdc4692 100644
--- a/sfm/compliance.py
+++ b/sfm/compliance.py
@@ -120,6 +120,7 @@ def draw_compliance_chart(ax, channels: Dict[str, Sequence[float]], sps: float)
     ax.set_yscale("log")
     ax.set_xlim(1, 100)
     ax.set_ylim(0.0394, 10)
+    ax.set_box_aspect(1)   # square plot box (log-log compliance charts are square)
     xt = [1, 2, 5, 10, 20, 50, 100]
     yt = [0.0394, 0.05, 0.1, 0.2, 0.5, 1, 2, 5, 10]
     ax.xaxis.set_major_locator(FixedLocator(xt)); ax.xaxis.set_minor_locator(NullLocator())