diff --git a/AlgebraicDataflowArchitectureModel/models/CustomerOffice.model b/AlgebraicDataflowArchitectureModel/models/CustomerOffice.model
index 4f94bd2..f140bff 100644
--- a/AlgebraicDataflowArchitectureModel/models/CustomerOffice.model
+++ b/AlgebraicDataflowArchitectureModel/models/CustomerOffice.model
@@ -22,12 +22,12 @@
 	in customerA_off(c, sync(z, u, v)) == z
 	in companyC1_add(a1, sync(z, u, v)) == u
 	in companyC2_add(a2, sync(z, u, v)) == v
-	out customerA_add(a3:String, sync(z, u, v)) == if(eq(z, C1), u, if(eq(z, C2), v, nil))
+	out customerA_add(a3:String, sync(z, u, v)) == if(eq(z, C1), u, if(eq(z, C2), v, null))
 }
 
 channel CB {
 	in customerB_off(c, sync(z, u, v)) == z
 	in companyC1_add(a1, sync(z, u, v)) == u
 	in companyC2_add(a2, sync(z, u, v)) == v
-	out customerB_add(a3:String, sync(z, u, v)) == if(eq(z, C1), u, if(eq(z, C2), v, nil))
+	out customerB_add(a3:String, sync(z, u, v)) == if(eq(z, C1), u, if(eq(z, C2), v, null))
 }