diff --git a/gnu/image.scm b/gnu/image.scm
index a60d83b175b..75d489490dd 100644
--- a/gnu/image.scm
+++ b/gnu/image.scm
@@ -31,6 +31,7 @@
             partition-initializer
 
             image
+            image?
             image-name
             image-format
             image-target