diff --git a/src/Core/TT/Subst.idr b/src/Core/TT/Subst.idr
index 97790b6e07..1791910c0d 100644
--- a/src/Core/TT/Subst.idr
+++ b/src/Core/TT/Subst.idr
@@ -6,6 +6,8 @@ import Core.TT.Var
 
 import Data.SnocList
 
+import Libraries.Data.SnocList.SizeOf
+
 %default total
 
 public export
diff --git a/src/Core/TT/Term.idr b/src/Core/TT/Term.idr
index 90e086d28e..17f915b9be 100644
--- a/src/Core/TT/Term.idr
+++ b/src/Core/TT/Term.idr
@@ -6,6 +6,7 @@ import Core.FC
 
 import Core.Name
 import Core.Name.Scoped
+import Core.Name.CompatibleVars
 import Core.TT.Binder
 import Core.TT.Primitive
 import Core.TT.Var
@@ -13,6 +14,8 @@ import Core.TT.Var
 import Data.List
 import Data.SnocList
 
+import Libraries.Data.SnocList.SizeOf
+
 %default total
 
 ------------------------------------------------------------------------
diff --git a/src/Core/TT/Term/Subst.idr b/src/Core/TT/Term/Subst.idr
index be37646da6..9e7c880e21 100644
--- a/src/Core/TT/Term/Subst.idr
+++ b/src/Core/TT/Term/Subst.idr
@@ -10,6 +10,8 @@ import Core.TT.Var
 
 import Data.SnocList
 
+import Libraries.Data.SnocList.SizeOf
+
 %default total
 
 public export