diff --git a/src/libexpr/eval-gc.hh b/src/libexpr/eval-gc.hh
index 8f0b32c1c..f3b699b54 100644
--- a/src/libexpr/eval-gc.hh
+++ b/src/libexpr/eval-gc.hh
@@ -13,6 +13,8 @@
 
 #else
 
+#  include <memory>
+
 /* Some dummy aliases for Boehm GC definitions to reduce the number of
    #ifdefs. */