diff --git a/basis/compiler/cfg/instructions/instructions.factor b/basis/compiler/cfg/instructions/instructions.factor
index bd93214297..b98e24253d 100644
--- a/basis/compiler/cfg/instructions/instructions.factor
+++ b/basis/compiler/cfg/instructions/instructions.factor
@@ -153,7 +153,12 @@ INSN: ##set-alien-double < ##alien-setter ;
 ! Memory allocation
 INSN: ##allot < ##flushable size class temp ;
 
-UNION: ##allocation ##allot ##box-float ##box-alien ##integer>bignum ;
+UNION: ##allocation
+##allot
+##box-float
+##box-alien
+##box-displaced-alien
+##integer>bignum ;
 
 INSN: ##write-barrier < ##effect card# table ;
 
diff --git a/basis/compiler/tests/codegen.factor b/basis/compiler/tests/codegen.factor
index 5f06fc8d2a..d45b4aa151 100644
--- a/basis/compiler/tests/codegen.factor
+++ b/basis/compiler/tests/codegen.factor
@@ -401,4 +401,10 @@ cell 4 = [
     dup [ [ 1 fixnum+fast ] dip ] [ [ drop 1 ] dip ] if ;
 
 [ 2 t ] [ 0 t global-dcn-bug-1 ] unit-test
-[ 1 f ] [ 0 f global-dcn-bug-1 ] unit-test
\ No newline at end of file
+[ 1 f ] [ 0 f global-dcn-bug-1 ] unit-test
+
+! Forgot a GC check
+: missing-gc-check-1 ( a -- b ) { fixnum } declare <alien> ;
+: missing-gc-check-2 ( -- ) 10000000 [ missing-gc-check-1 drop ] each-integer ;
+
+[ ] [ missing-gc-check-2 ] unit-test
\ No newline at end of file