diff --git a/src/source_damage_isoBrittle.f90 b/src/source_damage_isoBrittle.f90
index 16f4273bb..cf43fdfb8 100644
--- a/src/source_damage_isoBrittle.f90
+++ b/src/source_damage_isoBrittle.f90
@@ -8,6 +8,7 @@ module source_damage_isoBrittle
   use prec
   use debug
   use IO
+  use math
   use material
   use config