diff --git a/src/kernel/environment.cpp b/src/kernel/environment.cpp
index ebe9a9dca..e99a65b67 100644
--- a/src/kernel/environment.cpp
+++ b/src/kernel/environment.cpp
@@ -4,6 +4,8 @@ Released under Apache 2.0 license as described in the file LICENSE.
 
 Author: Leonardo de Moura
 */
+#include <utility>
+#include <vector>
 #include <limits>
 #include "kernel/environment.h"
 #include "kernel/kernel_exception.h"
@@ -58,10 +60,10 @@ optional<definition> environment::find(name const & n) const {
 }
 
 definition environment::get(name const & n) const {
-   definition const * r = m_definitions.find(n);
-   if (!r)
-       throw_unknown_declaration(*this, n);
-   return *r;
+    definition const * r = m_definitions.find(n);
+    if (!r)
+        throw_unknown_declaration(*this, n);
+    return *r;
 }
 
 [[ noreturn ]] void throw_incompatible_environment(environment const & env) {
diff --git a/src/kernel/environment.h b/src/kernel/environment.h
index 5766ac30e..6e522c98b 100644
--- a/src/kernel/environment.h
+++ b/src/kernel/environment.h
@@ -7,6 +7,7 @@ Author: Leonardo de Moura
 #pragma once
 #include <utility>
 #include <memory>
+#include <vector>
 #include "util/rc.h"
 #include "util/optional.h"
 #include "util/list.h"