diff --git a/netmap/policy.go b/netmap/policy.go
index 28b5390..2884c3f 100644
--- a/netmap/policy.go
+++ b/netmap/policy.go
@@ -551,16 +551,17 @@ func writeFilterStringTo(w io.StringWriter, f netmap.Filter) error {
 // DecodeString decodes PlacementPolicy from the string composed using
 // WriteStringTo. Returns error if s is malformed.
 func (p *PlacementPolicy) DecodeString(s string) error {
+	var v policyVisitor
+
 	input := antlr.NewInputStream(s)
 	lexer := parser.NewQueryLexer(input)
 	lexer.RemoveErrorListeners()
+	lexer.AddErrorListener(&v)
 	stream := antlr.NewCommonTokenStream(lexer, 0)
 
 	pp := parser.NewQuery(stream)
 	pp.BuildParseTrees = true
 
-	var v policyVisitor
-
 	pp.RemoveErrorListeners()
 	pp.AddErrorListener(&v)
 	pl := pp.Policy().Accept(&v)
diff --git a/netmap/policy_test.go b/netmap/policy_test.go
index 0c2782c..2d04313 100644
--- a/netmap/policy_test.go
+++ b/netmap/policy_test.go
@@ -25,8 +25,9 @@ SELECT 1 IN City FROM SPBSSD AS SPB
 FILTER City EQ SPB AND SSD EQ true OR City EQ SPB AND Rating GE 5 AS SPBSSD`,
 	}
 
+	var p PlacementPolicy
+
 	for _, testCase := range testCases {
-		var p PlacementPolicy
 
 		require.NoError(t, p.DecodeString(testCase))
 
@@ -35,6 +36,14 @@ FILTER City EQ SPB AND SSD EQ true OR City EQ SPB AND Rating GE 5 AS SPBSSD`,
 
 		require.Equal(t, testCase, b.String())
 	}
+
+	invalidTestCases := []string{
+		`?REP 1`,
+	}
+
+	for i := range invalidTestCases {
+		require.Error(t, p.DecodeString(invalidTestCases[i]), "#%d", i)
+	}
 }
 
 func TestPlacementPolicyEncoding(t *testing.T) {