diff --git a/src/proj.rs b/src/proj.rs
index fedeb631..b579bb51 100644
--- a/src/proj.rs
+++ b/src/proj.rs
@@ -487,6 +487,8 @@ pub struct Proj {
     area: Option<*mut PJ_AREA>,
 }
 
+unsafe impl Send for Proj {}
+
 impl Proj {
     /// Try to create a new transformation object
     ///