diff --git a/src/fiats/neural_network_s.F90 b/src/fiats/neural_network_s.F90
index b3e694d9f..33dff6c1c 100644
--- a/src/fiats/neural_network_s.F90
+++ b/src/fiats/neural_network_s.F90
@@ -659,7 +659,7 @@ elemental module subroutine double_precision_assert_conformable_with(self, neura
     block
       integer l
       logical layer_eq(ubound(lhs%nodes_,1))
-      real, parameter :: tolerance = 1.D-12
+      double precision, parameter :: tolerance = 1.D-12
 
       associate(n => lhs%nodes_)
         do concurrent(l = 1:ubound(n,1))