diff --git a/tests/baselines/reference/unionAndIntersectionInference3.js b/tests/baselines/reference/unionAndIntersectionInference3.js
new file mode 100644
index 00000000000..4cc0c2f667e
--- /dev/null
+++ b/tests/baselines/reference/unionAndIntersectionInference3.js
@@ -0,0 +1,12 @@
+//// [unionAndIntersectionInference3.ts]
+// Repro from #30720
+
+type Maybe<T> = T | undefined;
+declare function concatMaybe<T>(...args: (Maybe<T> | Maybe<T>[])[]): T[];
+concatMaybe([1, 2, 3], 4);
+
+
+//// [unionAndIntersectionInference3.js]
+"use strict";
+// Repro from #30720
+concatMaybe([1, 2, 3], 4);
diff --git a/tests/baselines/reference/unionAndIntersectionInference3.symbols b/tests/baselines/reference/unionAndIntersectionInference3.symbols
new file mode 100644
index 00000000000..be24bc0cc77
--- /dev/null
+++ b/tests/baselines/reference/unionAndIntersectionInference3.symbols
@@ -0,0 +1,21 @@
+=== tests/cases/conformance/types/typeRelationships/typeInference/unionAndIntersectionInference3.ts ===
+// Repro from #30720
+
+type Maybe<T> = T | undefined;
+>Maybe : Symbol(Maybe, Decl(unionAndIntersectionInference3.ts, 0, 0))
+>T : Symbol(T, Decl(unionAndIntersectionInference3.ts, 2, 11))
+>T : Symbol(T, Decl(unionAndIntersectionInference3.ts, 2, 11))
+
+declare function concatMaybe<T>(...args: (Maybe<T> | Maybe<T>[])[]): T[];
+>concatMaybe : Symbol(concatMaybe, Decl(unionAndIntersectionInference3.ts, 2, 30))
+>T : Symbol(T, Decl(unionAndIntersectionInference3.ts, 3, 29))
+>args : Symbol(args, Decl(unionAndIntersectionInference3.ts, 3, 32))
+>Maybe : Symbol(Maybe, Decl(unionAndIntersectionInference3.ts, 0, 0))
+>T : Symbol(T, Decl(unionAndIntersectionInference3.ts, 3, 29))
+>Maybe : Symbol(Maybe, Decl(unionAndIntersectionInference3.ts, 0, 0))
+>T : Symbol(T, Decl(unionAndIntersectionInference3.ts, 3, 29))
+>T : Symbol(T, Decl(unionAndIntersectionInference3.ts, 3, 29))
+
+concatMaybe([1, 2, 3], 4);
+>concatMaybe : Symbol(concatMaybe, Decl(unionAndIntersectionInference3.ts, 2, 30))
+
diff --git a/tests/baselines/reference/unionAndIntersectionInference3.types b/tests/baselines/reference/unionAndIntersectionInference3.types
new file mode 100644
index 00000000000..8497cb1e516
--- /dev/null
+++ b/tests/baselines/reference/unionAndIntersectionInference3.types
@@ -0,0 +1,19 @@
+=== tests/cases/conformance/types/typeRelationships/typeInference/unionAndIntersectionInference3.ts ===
+// Repro from #30720
+
+type Maybe<T> = T | undefined;
+>Maybe : Maybe<T>
+
+declare function concatMaybe<T>(...args: (Maybe<T> | Maybe<T>[])[]): T[];
+>concatMaybe : <T>(...args: (T | Maybe<T>[] | undefined)[]) => T[]
+>args : (T | Maybe<T>[] | undefined)[]
+
+concatMaybe([1, 2, 3], 4);
+>concatMaybe([1, 2, 3], 4) : number[]
+>concatMaybe : <T>(...args: (T | Maybe<T>[] | undefined)[]) => T[]
+>[1, 2, 3] : number[]
+>1 : 1
+>2 : 2
+>3 : 3
+>4 : 4
+