diff --git a/src/library/blast/discr_tree.cpp b/src/library/blast/discr_tree.cpp
index 495b5e9a0..240ca62e4 100644
--- a/src/library/blast/discr_tree.cpp
+++ b/src/library/blast/discr_tree.cpp
@@ -171,7 +171,7 @@ auto discr_tree::insert_erase_app(node && n, bool is_root, expr const & e, buffe
     if (is_constant(fn) || is_local(fn)) {
         if (!is_root)
             todo.push_back(mk_pair(*g_delimiter, false));
-        fun_info info = get_fun_info(fn);
+        fun_info info = get_fun_info(fn, args.size());
         buffer<param_info> pinfos;
         to_buffer(info.get_params_info(), pinfos);
         lean_assert(pinfos.size() == args.size());
@@ -281,7 +281,7 @@ bool discr_tree::find_app(node const & n, expr const & e, list<pair<expr, bool>>
     buffer<expr> args;
     expr const & f = get_app_args(e, args);
     if (is_constant(f) || is_local(f)) {
-        fun_info info = get_fun_info(f);
+        fun_info info = get_fun_info(f, args.size());
         buffer<param_info> pinfos;
         to_buffer(info.get_params_info(), pinfos);
         lean_assert(pinfos.size() == args.size());
diff --git a/tests/lean/run/blast_discr_tree_bug.lean b/tests/lean/run/blast_discr_tree_bug.lean
new file mode 100644
index 000000000..d7a0b4116
--- /dev/null
+++ b/tests/lean/run/blast_discr_tree_bug.lean
@@ -0,0 +1,18 @@
+open subtype nat
+
+constant f : Π (a : nat), {b : nat | b > a} → nat
+
+definition f_flat (a : nat) (b : nat) (p : b > a) : nat :=
+f a (tag b p)
+
+definition greater [reducible] (a : nat) := {b : nat | b > a}
+set_option blast.recursion.structure true
+
+definition f_flat_def [simp] (a : nat) (b : nat) (p : b > a) : f a (tag b p) = f_flat a b p :=
+rfl
+
+definition has_property_tag [simp] {A : Type} {p : A → Prop} (a : A) (h : p a) : has_property (tag a h) = h :=
+rfl
+
+lemma to_f_flat : ∀ (a : nat) (b : greater a), f a b = f_flat a (elt_of b) (has_property b) :=
+by rec_simp