diff --git a/src/library/compiler/compiler.cpp b/src/library/compiler/compiler.cpp
index c36a7fb409..e68789f925 100644
--- a/src/library/compiler/compiler.cpp
+++ b/src/library/compiler/compiler.cpp
@@ -20,6 +20,7 @@ Author: Leonardo de Moura
 #include "library/compiler/erase_irrelevant.h"
 #include "library/compiler/specialize.h"
 #include "library/compiler/eager_lambda_lifting.h"
+#include "library/compiler/implemented_by_attribute.h"
 #include "library/compiler/lambda_lifting.h"
 #include "library/compiler/extract_closed.h"
 #include "library/compiler/reduce_arity.h"
@@ -185,7 +186,9 @@ environment compile(environment const & env, options const & opts, names cs) {
 
     if (length(cs) == 1) {
         name c = get_real_name(head(cs));
-        if (skip_code_generation(env, c)) {
+        if (has_implemented_by_attribute(env, c))
+            return env;
+        if (is_extern_or_init_constant(env, c)) {
             /* Generate boxed version for extern/native constant if needed. */
             return ir::add_extern(env, c);
         }
diff --git a/src/library/compiler/extern_attribute.cpp b/src/library/compiler/extern_attribute.cpp
index ee88f206b4..447f892920 100644
--- a/src/library/compiler/extern_attribute.cpp
+++ b/src/library/compiler/extern_attribute.cpp
@@ -31,8 +31,8 @@ bool is_extern_constant(environment const & env, name const & c) {
     return static_cast<bool>(get_extern_attr_data(env, c));
 }
 
-bool skip_code_generation(environment const & env, name const & c) {
-    if (is_extern_constant(env, c) || has_implemented_by_attribute(env, c)) {
+bool is_extern_or_init_constant(environment const & env, name const & c) {
+    if (is_extern_constant(env, c)) {
         return true;
     } else if (auto info = env.find(c)) {
         // `declarations marked with `init`
@@ -81,7 +81,7 @@ bool get_extern_borrowed_info(environment const & env, name const & c, buffer<bo
 }
 
 optional<expr> get_extern_constant_ll_type(environment const & env, name const & c) {
-    if (skip_code_generation(env, c)) {
+    if (is_extern_or_init_constant(env, c)) {
         unsigned arity = 0;
         expr type = env.get(c).get_type();
         type_checker::state st(env);
diff --git a/src/library/compiler/extern_attribute.h b/src/library/compiler/extern_attribute.h
index db6ed58817..84c6d3194b 100644
--- a/src/library/compiler/extern_attribute.h
+++ b/src/library/compiler/extern_attribute.h
@@ -9,7 +9,7 @@ Authors: Leonardo de Moura
 #include "kernel/environment.h"
 namespace lean {
 bool is_extern_constant(environment const & env, name const & c);
-bool skip_code_generation(environment const & env, name const & c);
+bool is_extern_or_init_constant(environment const & env, name const & c);
 optional<expr> get_extern_constant_ll_type(environment const & env, name const & c);
 optional<unsigned> get_extern_constant_arity(environment const & env, name const & c);
 typedef object_ref extern_attr_data_value;