diff --git a/data/media/icons/horizontal-symbolic.svg b/data/media/icons/horizontal-symbolic.svg
index 0a66efa..c36cb1e 100644
--- a/data/media/icons/horizontal-symbolic.svg
+++ b/data/media/icons/horizontal-symbolic.svg
@@ -1,2 +1,18 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<svg xmlns="http://www.w3.org/2000/svg" width="16px" height="16px" viewBox="0 0 16 16"><path d="M1.577 5.537h12.845v4.926H1.577z" fill="none" stroke="#000"/></svg>
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<svg
+   width="16px"
+   height="16px"
+   viewBox="0 0 16 16"
+   version="1.1"
+   id="svg1"
+   xmlns="http://www.w3.org/2000/svg"
+   xmlns:svg="http://www.w3.org/2000/svg">
+  <defs
+     id="defs1" />
+  <path
+     d="M1.577 5.537h12.845v4.926H1.577z"
+     fill="none"
+     stroke="#000"
+     id="path1"
+     style="stroke-width:1;stroke-dasharray:none" />
+</svg>
diff --git a/src/unit.py b/src/unit.py
index d683d39..7e98e48 100644
--- a/src/unit.py
+++ b/src/unit.py
@@ -377,10 +377,10 @@ def _draw_vertical(self, ctx_text, min_size: int, show_grid: bool) -> None:
         self.context.ctx.translate(-self.context.width, 0)
 
     def px_per_tick_diagonal(self) -> float:
-        return (
-            self.px_per_tick_width
-            if self.context.width >= self.context.height
-            else self.px_per_tick_height
+        angle = math.atan2(self.context.height, self.context.width)
+        return math.sqrt(
+            self.px_per_tick_width**2 * math.cos(angle) ** 2
+            + self.px_per_tick_height**2 * math.sin(angle) ** 2
         )
 
     def _draw_diag_1(self, ctx_text, min_size: int) -> None: