diff --git a/src/opt_disl.f90 b/src/opt_disl.f90
index 00886e5..79c45bf 100644
--- a/src/opt_disl.f90
+++ b/src/opt_disl.f90
@@ -292,6 +292,7 @@ module opt_disl
         end select
 
         if(loop_radius < 0.0_dp) then 
+                ALLOCATE(xLoop(4,3))
                 xLoop(:,:) = 0.d0
                 xLoop(1,a1) = centroid(1) - loop_radius
                 xLoop(1,a2) = centroid(2) - loop_radius