diff --git a/cmake/Modules/opm-core-prereqs.cmake b/cmake/Modules/opm-core-prereqs.cmake
index 4f8a8aa6..9f668107 100644
--- a/cmake/Modules/opm-core-prereqs.cmake
+++ b/cmake/Modules/opm-core-prereqs.cmake
@@ -7,6 +7,7 @@ set (opm-core_CONFIG_VAR
 	HAVE_SUITESPARSE_UMFPACK_H
 	HAVE_DUNE_ISTL
 	HAVE_MPI
+	HAVE_PETSC
 	)
 
 # dependencies