diff --git a/src/lib/converter/factories/signature.ts b/src/lib/converter/factories/signature.ts
index 82233f876..c94275c3e 100644
--- a/src/lib/converter/factories/signature.ts
+++ b/src/lib/converter/factories/signature.ts
@@ -68,7 +68,9 @@ export function createSignature(
     } else {
         sigRef.type = context.converter.convertType(
             context.withScope(sigRef),
-            signature.getReturnType()
+            (declaration?.kind === ts.SyntaxKind.FunctionDeclaration &&
+                declaration.type) ||
+                signature.getReturnType()
         );
     }
 
@@ -108,11 +110,26 @@ function convertParameters(
             declaration
         );
 
+        let type: ts.Type | ts.TypeNode;
+        if (
+            declaration &&
+            ts.isParameter(declaration) &&
+            ts.isFunctionDeclaration(declaration.parent) &&
+            declaration.type
+        ) {
+            type = declaration.type;
+        } else if (declaration) {
+            type = context.checker.getTypeOfSymbolAtLocation(
+                param,
+                declaration
+            );
+        } else {
+            type = param.type;
+        }
+
         paramRefl.type = context.converter.convertType(
             context.withScope(paramRefl),
-            declaration
-                ? context.checker.getTypeOfSymbolAtLocation(param, declaration)
-                : param.type
+            type
         );
 
         let isOptional = false;
diff --git a/src/lib/converter/types.ts b/src/lib/converter/types.ts
index 23a8170c8..4ade28055 100644
--- a/src/lib/converter/types.ts
+++ b/src/lib/converter/types.ts
@@ -579,6 +579,17 @@ const referenceConverter: TypeConverter<
 > = {
     kind: [ts.SyntaxKind.TypeReference],
     convert(context, node) {
+        const isArray =
+            context.checker.typeToTypeNode(
+                context.checker.getTypeAtLocation(node.typeName),
+                void 0,
+                ts.NodeBuilderFlags.IgnoreErrors
+            )?.kind === ts.SyntaxKind.ArrayType;
+
+        if (isArray) {
+            return new ArrayType(convertType(context, node.typeArguments?.[0]));
+        }
+
         const symbol = context.expectSymbolAtLocation(node.typeName);
 
         const name = node.typeName.getText();
diff --git a/src/test/converter/alias/alias.ts b/src/test/converter/alias/alias.ts
index 2ea883479..17197dab9 100644
--- a/src/test/converter/alias/alias.ts
+++ b/src/test/converter/alias/alias.ts
@@ -65,3 +65,11 @@ export namespace GH1330 {
 export namespace GH1408 {
     export declare function foo<T extends unknown[]>(): T;
 }
+
+export namespace GH1454 {
+    export type Foo = string | number;
+    export type Bar = string | number;
+
+    export declare function bar(x: Bar): Bar;
+    export declare function foo(x: Foo): Foo;
+}
diff --git a/src/test/converter/alias/specs.json b/src/test/converter/alias/specs.json
index 9d60e0d99..8c075064c 100644
--- a/src/test/converter/alias/specs.json
+++ b/src/test/converter/alias/specs.json
@@ -238,6 +238,143 @@
         }
       ]
     },
+    {
+      "id": 43,
+      "name": "GH1454",
+      "kind": 2,
+      "kindString": "Namespace",
+      "flags": {},
+      "children": [
+        {
+          "id": 51,
+          "name": "Bar",
+          "kind": 4194304,
+          "kindString": "Type alias",
+          "flags": {},
+          "type": {
+            "type": "union",
+            "types": [
+              {
+                "type": "intrinsic",
+                "name": "string"
+              },
+              {
+                "type": "intrinsic",
+                "name": "number"
+              }
+            ]
+          }
+        },
+        {
+          "id": 50,
+          "name": "Foo",
+          "kind": 4194304,
+          "kindString": "Type alias",
+          "flags": {},
+          "type": {
+            "type": "union",
+            "types": [
+              {
+                "type": "intrinsic",
+                "name": "string"
+              },
+              {
+                "type": "intrinsic",
+                "name": "number"
+              }
+            ]
+          }
+        },
+        {
+          "id": 44,
+          "name": "bar",
+          "kind": 64,
+          "kindString": "Function",
+          "flags": {},
+          "signatures": [
+            {
+              "id": 45,
+              "name": "bar",
+              "kind": 4096,
+              "kindString": "Call signature",
+              "flags": {},
+              "parameters": [
+                {
+                  "id": 46,
+                  "name": "x",
+                  "kind": 32768,
+                  "kindString": "Parameter",
+                  "flags": {},
+                  "type": {
+                    "type": "reference",
+                    "id": 51,
+                    "name": "Bar"
+                  }
+                }
+              ],
+              "type": {
+                "type": "reference",
+                "id": 51,
+                "name": "Bar"
+              }
+            }
+          ]
+        },
+        {
+          "id": 47,
+          "name": "foo",
+          "kind": 64,
+          "kindString": "Function",
+          "flags": {},
+          "signatures": [
+            {
+              "id": 48,
+              "name": "foo",
+              "kind": 4096,
+              "kindString": "Call signature",
+              "flags": {},
+              "parameters": [
+                {
+                  "id": 49,
+                  "name": "x",
+                  "kind": 32768,
+                  "kindString": "Parameter",
+                  "flags": {},
+                  "type": {
+                    "type": "reference",
+                    "id": 50,
+                    "name": "Foo"
+                  }
+                }
+              ],
+              "type": {
+                "type": "reference",
+                "id": 50,
+                "name": "Foo"
+              }
+            }
+          ]
+        }
+      ],
+      "groups": [
+        {
+          "title": "Type aliases",
+          "kind": 4194304,
+          "children": [
+            51,
+            50
+          ]
+        },
+        {
+          "title": "Functions",
+          "kind": 64,
+          "children": [
+            44,
+            47
+          ]
+        }
+      ]
+    },
     {
       "id": 21,
       "name": "HorribleRecursiveTypeThatShouldNotBeUsedByAnyone",
@@ -746,7 +883,8 @@
       "kind": 2,
       "children": [
         28,
-        39
+        39,
+        43
       ]
     },
     {
diff --git a/src/test/converter/function/specs.json b/src/test/converter/function/specs.json
index 8d3578909..ad639e962 100644
--- a/src/test/converter/function/specs.json
+++ b/src/test/converter/function/specs.json
@@ -520,16 +520,16 @@
                     "type": "union",
                     "types": [
                       {
-                        "type": "intrinsic",
-                        "name": "undefined"
+                        "type": "reference",
+                        "name": "T"
                       },
                       {
                         "type": "literal",
                         "value": null
                       },
                       {
-                        "type": "reference",
-                        "name": "T"
+                        "type": "intrinsic",
+                        "name": "undefined"
                       }
                     ]
                   }
@@ -1004,16 +1004,16 @@
                     "type": "union",
                     "types": [
                       {
-                        "type": "intrinsic",
-                        "name": "undefined"
+                        "type": "reference",
+                        "name": "T"
                       },
                       {
                         "type": "literal",
                         "value": null
                       },
                       {
-                        "type": "reference",
-                        "name": "T"
+                        "type": "intrinsic",
+                        "name": "undefined"
                       }
                     ]
                   }