diff --git a/vlib/math/complex/complex.v b/vlib/math/complex/complex.v
index 2883dab4fe..39d848cad2 100644
--- a/vlib/math/complex/complex.v
+++ b/vlib/math/complex/complex.v
@@ -7,7 +7,7 @@ module complex
 import math
 
 pub struct Complex {
-pub:
+pub mut:
 	re f64
 	im f64
 }