diff --git a/pineappl/src/lagrange_subgrid.rs b/pineappl/src/lagrange_subgrid.rs
index b2ac386b..80e62a01 100644
--- a/pineappl/src/lagrange_subgrid.rs
+++ b/pineappl/src/lagrange_subgrid.rs
@@ -493,9 +493,9 @@ impl Subgrid for LagrangeSubgridV2 {
         let y2 = fy(ntuple.x2);
         let tau = ftau(ntuple.q2);
 
-        if ntuple.q2 == 0.0 {
+        if self.static_q2 == 0.0 {
             self.static_q2 = ntuple.q2;
-        } else if self.static_q2 != ntuple.q2 {
+        } else if (self.static_q2 != 1.0) && (self.static_q2 != ntuple.q2) {
             self.static_q2 = -1.0;
         }