diff --git a/def.go b/def.go
index b05a12e..b4493e8 100644
--- a/def.go
+++ b/def.go
@@ -603,6 +603,7 @@ type Fpdf struct {
 	}
 	spotColorMap           map[string]spotColorType // Map of named ink-based colors
 	userUnderlineThickness float64                  // A custom user underline thickness multiplier.
+	density                float64                  // Documents density in dpi (72 by default)
 }
 
 type encType struct {