diff --git a/c/containers/local_stack.h b/c/containers/local_stack.h
index 656703219..417f75362 100644
--- a/c/containers/local_stack.h
+++ b/c/containers/local_stack.h
@@ -123,7 +123,11 @@ static inline void local_stack_frame_define(local_stack_frame_t* pframe, char* v
 
 	// xxx temp -- make a single method
 	mv_free(&pentry->value.u.mlrval); // xxx temp -- make value-free
-	pentry->value = mlhmmv_value_transfer_terminal(val); // xxx deep-copy?
+	if (mv_is_absent(&val)) {
+		mv_free(&val); // xxx confusing ownership semantics
+	} else {
+		pentry->value = mlhmmv_value_transfer_terminal(val); // xxx deep-copy?
+	}
 }
 
 static inline void local_stack_frame_xdefine(local_stack_frame_t* pframe, char* variable_name, // xxx rename
@@ -148,8 +152,12 @@ static inline void local_stack_frame_xdefine(local_stack_frame_t* pframe, char*
 	}
 
 	// xxx temp -- make a single method
-	mlhmmv_free_submap(pentry->value); // xxx rename
-	pentry->value = xval;
+	if (xval.is_terminal && mv_is_absent(&xval.u.mlrval)) {
+		mlhmmv_free_submap(xval); // xxx confusing ownership semantics
+	} else {
+		mlhmmv_free_submap(pentry->value); // xxx rename
+		pentry->value = xval;
+	}
 }
 
 
diff --git a/c/mapping/mlr_dsl_cst_assignment_statements.c b/c/mapping/mlr_dsl_cst_assignment_statements.c
index 6795704ee..8698fea59 100644
--- a/c/mapping/mlr_dsl_cst_assignment_statements.c
+++ b/c/mapping/mlr_dsl_cst_assignment_statements.c
@@ -239,14 +239,11 @@ static void handle_local_variable_definition_from_val( // xxx mapvar
 
 	rval_evaluator_t* prhs_evaluator = pstate->prhs_evaluator;
 	mv_t val = prhs_evaluator->pprocess_func(prhs_evaluator->pvstate, pvars);
-	if (mv_is_present(&val)) {
-		local_stack_frame_t* pframe = local_stack_get_top_frame(pvars->plocal_stack);
-		local_stack_frame_define(pframe,
-			pstate->lhs_variable_name, pstate->lhs_frame_relative_index,
-			pstate->lhs_type_mask, val);
-	} else {
-		mv_free(&val);
-	}
+
+	local_stack_frame_t* pframe = local_stack_get_top_frame(pvars->plocal_stack);
+	local_stack_frame_define(pframe,
+		pstate->lhs_variable_name, pstate->lhs_frame_relative_index,
+		pstate->lhs_type_mask, val);
 }
 
 // ----------------------------------------------------------------
@@ -260,14 +257,10 @@ static void handle_local_variable_definition_from_xval( // xxx mapvar
 	rxval_evaluator_t* prhs_xevaluator = pstate->prhs_xevaluator;
 	mlhmmv_value_t xval = prhs_xevaluator->pprocess_func(prhs_xevaluator->pvstate, pvars);
 
-	if (!xval.is_terminal || mv_is_present(&xval.u.mlrval)) { // xxx funcify
-		local_stack_frame_t* pframe = local_stack_get_top_frame(pvars->plocal_stack);
-		local_stack_frame_xdefine(pframe, // xxx rename
-			pstate->lhs_variable_name, pstate->lhs_frame_relative_index, pstate->lhs_type_mask,
-			xval);
-	} else {
-		mlhmmv_free_submap(xval); // xxx rename
-	}
+	local_stack_frame_t* pframe = local_stack_get_top_frame(pvars->plocal_stack);
+	local_stack_frame_xdefine(pframe, // xxx rename
+		pstate->lhs_variable_name, pstate->lhs_frame_relative_index, pstate->lhs_type_mask,
+		xval);
 }
 
 // ================================================================
diff --git a/c/reg_test/run b/c/reg_test/run
index dbc0bd1f3..11acb2a78 100755
--- a/c/reg_test/run
+++ b/c/reg_test/run
@@ -5375,7 +5375,7 @@ run_mlr --from $indir/xyz2 put -q 'c[1][2] = 3; @o = c; dump @o'
 announce MAPVAR ASSIGNMENTS TO MAP-TYPED LOCAL
 
 run_mlr         --from $indir/xyz2 put -q 'map o = {"a":1, "b": {"x":8,"y":9}, "c":3}; dump o'
-run_mlr         --from $indir/xyz2 put -q 'map o = @o; dump o'
+mlr_expect_fail --from $indir/xyz2 put -q 'map o = @o; dump o'
 run_mlr         --from $indir/xyz2 put -q 'map o = {"a":1, "b": {"x":8,"y":9}, "c":3}; o = o; dump o'
 mlr_expect_fail --from $indir/xyz2 put -q '@a = 1; map o = @a; dump o'
 run_mlr         --from $indir/xyz2 put -q '@b[1] = 2; map o = @b; dump o'
diff --git a/c/todo.txt b/c/todo.txt
index a6b3bafe0..7f3686d27 100644
--- a/c/todo.txt
+++ b/c/todo.txt
@@ -1,7 +1,8 @@
 ================================================================
 BUGFIXES
 
-:D
+* mlr --from ./reg_test/input/xyz2 put -q 'a = 1; map o = a; dump o'
+  UMR?
 
 ================================================================
 NON-RELEASE:
@@ -117,6 +118,9 @@ k assign LHS localvar           ? assign RHS oosvar
 k assign LHS localvar           ? assign RHS localvar
 - assign LHS localvar           ? assign RHS func-retval
 
+----------------------------------------------------------------
+* 'not yet' UT cases
+
 ----------------------------------------------------------------
 ! we are going to need builtin functions which deal with maps.
   - length(@map) and length(map), proxy for NF. make it work with length({...}) and length($*).