diff --git a/Test/Proofs.lean b/Test/Proofs.lean
index 65f099f..1903306 100644
--- a/Test/Proofs.lean
+++ b/Test/Proofs.lean
@@ -701,7 +701,7 @@ def test_nat_zero_add_alt: TestM Unit := do
       }
     ])
 
-def test_composite_tactic_failure: TestM Unit := do
+def test_tactic_failure_unresolved_goals : TestM Unit := do
   let state? ← startProof (.expr "∀ (p : Nat → Prop), ∃ (x : Nat), p (0 + x + 0)")
   let state0 ← match state? with
     | .some state => pure state
@@ -720,6 +720,25 @@ def test_composite_tactic_failure: TestM Unit := do
   let .failure messages ← state1.tacticOn 0 tactic | addTest $ assertUnreachable s!"{tactic} should fail"
   checkEq s!"{tactic} fails" messages #[s!"{← getFileName}:0:12: error: unsolved goals\np : Nat → Prop\n⊢ p 0\n"]
 
+def test_tactic_failure_synthesize_placeholder : TestM Unit := do
+  let state? ← startProof (.expr "∀ (p q r : Prop) (h : p → q), q ∧ r")
+  let state0 ← match state? with
+    | .some state => pure state
+    | .none => do
+      addTest $ assertUnreachable "Goal could not parse"
+      return ()
+
+  let tactic := "intro p q r h"
+  let state1 ← match ← state0.tacticOn 0 tactic with
+    | .success state => pure state
+    | other => do
+      addTest $ assertUnreachable $ other.toString
+      return ()
+
+  let tactic := "simpa [h] using And.imp_left h _"
+  let .failure messages ← state1.tacticOn 0 tactic | addTest $ assertUnreachable s!"{tactic} should fail"
+  checkEq s!"{tactic} fails" messages #[s!"{← getFileName}:0:12: error: unsolved goals\np : Nat → Prop\n⊢ p 0\n"]
+
 def suite (env: Environment): List (String × IO LSpec.TestSeq) :=
   let tests := [
     ("identity", test_identity),
@@ -732,7 +751,8 @@ def suite (env: Environment): List (String × IO LSpec.TestSeq) :=
     ("calc", test_calc),
     ("Nat.zero_add", test_nat_zero_add),
     ("Nat.zero_add alt", test_nat_zero_add_alt),
-    ("composite tactic failure", test_composite_tactic_failure),
+    ("tactic failure with unresolved goals", test_tactic_failure_unresolved_goals),
+    ("tactic failure with synthesize placeholder", test_tactic_failure_synthesize_placeholder),
   ]
   tests.map (fun (name, test) => (name, proofRunner env test))