diff --git a/io_curve_svg/import_svg.py b/io_curve_svg/import_svg.py
index 90cd89f775027ee9dce4ff35dec4d1b605ff7b3e..3bfdca328326aa31348ec08cf6281306a6a56264 100644
--- a/io_curve_svg/import_svg.py
+++ b/io_curve_svg/import_svg.py
@@ -32,9 +32,9 @@ from . import svg_colors
 # TODO: "em" and "ex" aren't actually supported
 SVGUnits = {"": 1.0,
             "px": 1.0,
-            "in": 90,
-            "mm": 90 / 25.4,
-            "cm": 90 / 2.54,
+            "in": 90.0 / 12.0 * 0.3048,
+            "mm": 90.0 / 1000.0,
+            "cm": 90.0 / 100.0,
             "pt": 1.25,
             "pc": 15.0,
             "em": 1.0,