diff --git a/src/library/class.cpp b/src/library/class.cpp
index 3c0d333fcf..79cf2336a0 100644
--- a/src/library/class.cpp
+++ b/src/library/class.cpp
@@ -473,7 +473,7 @@ list<expr> get_local_instances(type_checker & tc, list<expr> const & ctx, name c
 
 void initialize_class() {
     g_tmp_prefix = new name(name::mk_internal_unique_name());
-    g_source     = new name(*g_tmp_prefix, "source");
+    g_source     = new name("_source");
     g_class_name = new name("classes");
     g_key = new std::string("class");
     class_ext::initialize();
diff --git a/src/library/coercion.cpp b/src/library/coercion.cpp
index f2d4e0c0ab..239424213d 100644
--- a/src/library/coercion.cpp
+++ b/src/library/coercion.cpp
@@ -77,9 +77,8 @@ template class scoped_ext<coercion_config>;
 typedef scoped_ext<coercion_config> coercion_ext;
 
 void initialize_coercion() {
-    name p       = name::mk_internal_unique_name();
-    g_fun        = new name(p, "Fun");
-    g_sort       = new name(p, "Sort");
+    g_fun        = new name("_Fun");
+    g_sort       = new name("_Sort");
     g_class_name = new name("coercions");
     g_key        = new std::string("coerce");
     coercion_ext::initialize();
diff --git a/tests/lean/852.hlean b/tests/lean/852.hlean
new file mode 100644
index 0000000000..d6954c0b4c
--- /dev/null
+++ b/tests/lean/852.hlean
@@ -0,0 +1,5 @@
+import algebra.category.functor.equivalence
+
+-- print prefix category.equivalence
+
+check @category.equivalence.to._Fun
diff --git a/tests/lean/852.hlean.expected.out b/tests/lean/852.hlean.expected.out
new file mode 100644
index 0000000000..ce53e0e8bf
--- /dev/null
+++ b/tests/lean/852.hlean.expected.out
@@ -0,0 +1,6 @@
+category.equivalence.to._Fun :
+  Π {C : category.Precategory} {D : category.Precategory} (c : category.equivalence C D)
+  {a b : category.Precategory.carrier C},
+    category.hom a b →
+    category.hom (functor.to_fun_ob (category.equivalence.to_functor c) a)
+      (functor.to_fun_ob (category.equivalence.to_functor c) b)
diff --git a/tests/lean/binder_overload.lean.expected.out b/tests/lean/binder_overload.lean.expected.out
index 56929e9dcb..d972cc0aff 100644
--- a/tests/lean/binder_overload.lean.expected.out
+++ b/tests/lean/binder_overload.lean.expected.out
@@ -1,7 +1,7 @@
 {x : ℕ ∈ S | x > 0} : set ℕ
 {x : ℕ ∈ s | x > 0} : finset ℕ
-@set.sep.{1} nat (λ (x : nat), @gt.{1} nat 11.source.to.has_lt x 0) S : set.{1} nat
-@finset.sep.{1} nat (λ (a b : nat), nat.has_decidable_eq a b) (λ (x : nat), @gt.{1} nat 11.source.to.has_lt x 0)
+@set.sep.{1} nat (λ (x : nat), @gt.{1} nat _source.to.has_lt x 0) S : set.{1} nat
+@finset.sep.{1} nat (λ (a b : nat), nat.has_decidable_eq a b) (λ (x : nat), @gt.{1} nat _source.to.has_lt x 0)
   (λ (a : nat), nat.decidable_lt 0 a)
   s :
   finset.{1} nat
diff --git a/tests/lean/notation_priority.lean.expected.out b/tests/lean/notation_priority.lean.expected.out
index cd1835f9ac..af4e2ac54c 100644
--- a/tests/lean/notation_priority.lean.expected.out
+++ b/tests/lean/notation_priority.lean.expected.out
@@ -1,4 +1,4 @@
-@add.{1} nat 11.source.to.has_add a b : nat
-@add.{1} int 11.source.to.has_add_1 i j : int
-@add.{1} nat 11.source.to.has_add a b : nat
-@add.{1} int 11.source.to.has_add_1 i j : int
+@add.{1} nat _source.to.has_add a b : nat
+@add.{1} int _source.to.has_add_1 i j : int
+@add.{1} nat _source.to.has_add a b : nat
+@add.{1} int _source.to.has_add_1 i j : int
diff --git a/tests/lean/pp_all.lean.expected.out b/tests/lean/pp_all.lean.expected.out
index c5eae488b4..9aa2849640 100644
--- a/tests/lean/pp_all.lean.expected.out
+++ b/tests/lean/pp_all.lean.expected.out
@@ -1,2 +1,2 @@
 a + of_num b = 10 : Prop
-@eq.{1} nat (@add.{1} nat 11.source.to.has_add ((λ (x : nat), x) a) (nat.of_num 2)) 10 : Prop
+@eq.{1} nat (@add.{1} nat _source.to.has_add ((λ (x : nat), x) a) (nat.of_num 2)) 10 : Prop