diff --git a/types/mithril/index.d.ts b/types/mithril/index.d.ts
index f9a08ee74de508..a899924798cd30 100644
--- a/types/mithril/index.d.ts
+++ b/types/mithril/index.d.ts
@@ -43,18 +43,18 @@ declare namespace Mithril {
     }
 
     interface Hyperscript {
+        /** Creates a virtual element (Vnode). */
+        (selector: string, attributes: Attributes, ...children: Children[]): Vnode<any, any>;
+        /** Creates a virtual element (Vnode). */
+        (selector: string, ...children: Children[]): Vnode<any, any>;
+        /** Creates a virtual element (Vnode). */
+        <Attrs, State>(component: ComponentTypes<Attrs, State>, ...args: Children[]): Vnode<Attrs, State>;
         /** Creates a virtual element (Vnode). */
         <Attrs, State>(
             component: ComponentTypes<Attrs, State>,
             attributes: Attrs & CommonAttributes<Attrs, State>,
             ...args: Children[]
         ): Vnode<Attrs, State>;
-        /** Creates a virtual element (Vnode). */
-        (selector: string, attributes: Attributes, ...children: Children[]): Vnode<any, any>;
-        /** Creates a virtual element (Vnode). */
-        <Attrs, State>(component: ComponentTypes<Attrs, State>, ...args: Children[]): Vnode<Attrs, State>;
-        /** Creates a virtual element (Vnode). */
-        (selector: string, ...children: Children[]): Vnode<any, any>;
         /** Creates a fragment virtual element (Vnode). */
         fragment(
             attrs: CommonAttributes<any, any> & { [key: string]: any },
diff --git a/types/mithril/test/test-component.ts b/types/mithril/test/test-component.ts
index 360e113df67287..aa150202dccc34 100644
--- a/types/mithril/test/test-component.ts
+++ b/types/mithril/test/test-component.ts
@@ -51,6 +51,21 @@ m(comp2, { title: "", description: "" });
 // Correct use with lifecycle method
 m(comp2, { title: "", description: "", oncreate: v => `${v.attrs.title}\n${v.attrs.description}` });
 
+// Component attribute diagnostics
+interface NumberComponentAttrs {
+    min: number;
+}
+
+const numberComponent: Component<NumberComponentAttrs> = {
+    view() {
+        return null;
+    },
+};
+
+// Type 'string' is not assignable to type 'number'.
+// @ts-expect-error
+m(numberComponent, { min: "x" });
+
 // Properties missing
 // @ts-expect-error
 m(comp2, {});
diff --git a/types/negotiator/index.d.ts b/types/negotiator/index.d.ts
index 5f00d701ee0785..8eec9f0aee7f4e 100644
--- a/types/negotiator/index.d.ts
+++ b/types/negotiator/index.d.ts
@@ -12,7 +12,7 @@ declare class Negotiator {
      * @param [availableMediaTypes] When provided, returns the most preferred media type
      * from a list of available media types.
      */
-    mediaType(availableMediaTypes?: string[]): string | undefined;
+    mediaType(availableMediaTypes?: readonly string[]): string | undefined;
 
     /**
      * Returns an array of preferred media types ordered by the client preference
@@ -20,7 +20,7 @@ declare class Negotiator {
      * @param [availableMediaTypes] When provided, returns an array of preferred media
      * types ordered by priority from a list of available media types.
      */
-    mediaTypes(availableMediaTypes?: string[]): string[];
+    mediaTypes(availableMediaTypes?: readonly string[]): string[];
 
     /**
      * Returns the most preferred language from the client.
@@ -28,7 +28,7 @@ declare class Negotiator {
      * @param [availableLanguages] When provided, returns the most preferred language
      * from a list of available languages.
      */
-    language(availableLanguages?: string[]): string | undefined;
+    language(availableLanguages?: readonly string[]): string | undefined;
 
     /**
      * Returns an array of preferred languages ordered by the client preference.
@@ -36,7 +36,7 @@ declare class Negotiator {
      * @param [availableLanguages] When provided, returns an array of preferred languages
      * ordered by priority from a list of available languages.
      */
-    languages(availableLanguages?: string[]): string[];
+    languages(availableLanguages?: readonly string[]): string[];
 
     /**
      * Returns the most preferred charset from the client.
@@ -44,7 +44,7 @@ declare class Negotiator {
      * @param [availableCharsets] When provided, returns the most preferred charset
      * from a list of available charsets.
      */
-    charset(availableCharsets?: string[]): string | undefined;
+    charset(availableCharsets?: readonly string[]): string | undefined;
 
     /**
      * Returns an array of preferred charsets ordered by the client preference.
@@ -52,7 +52,7 @@ declare class Negotiator {
      * @param [availableCharsets] When provided, returns an array of preferred charsets
      * ordered by priority from a list of available charsets.
      */
-    charsets(availableCharsets?: string[]): string[];
+    charsets(availableCharsets?: readonly string[]): string[];
 
     /**
      * Returns the most preferred encoding from the client.
@@ -60,7 +60,7 @@ declare class Negotiator {
      * @param [availableEncodings] When provided, returns the most preferred encoding
      * from a list of available encodings.
      */
-    encoding(availableEncodings?: string[]): string | undefined;
+    encoding(availableEncodings?: readonly string[]): string | undefined;
 
     /**
      * Returns an array of preferred encodings ordered by the client preference.
@@ -68,11 +68,11 @@ declare class Negotiator {
      * @param [availableEncodings] When provided, returns an array of preferred encodings
      * ordered by priority from a list of available encodings.
      */
-    encodings(availableEncodings?: string[]): string[];
+    encodings(availableEncodings?: readonly string[]): string[];
 }
 
 declare namespace Negotiator {
     interface Headers {
-        [key: string]: string | string[] | undefined;
+        readonly [key: string]: string | (readonly string[]) | undefined;
     }
 }
diff --git a/types/negotiator/negotiator-tests.ts b/types/negotiator/negotiator-tests.ts
index 731505aebeaaf8..77cd4a8d44f76c 100644
--- a/types/negotiator/negotiator-tests.ts
+++ b/types/negotiator/negotiator-tests.ts
@@ -9,11 +9,11 @@ const request = {
         "Accept-Charset": "utf-8, iso-8859-1;q=0.8, utf-7;q=0.2",
         "Accept-Encoding": "gzip, compress;q=0.2, identity;q=0.5",
     },
-};
+} as const;
 
 const negotiator = new Negotiator(request);
 
-const availableMediaTypes = ["text/html", "text/plain", "application/json"];
+const availableMediaTypes = ["text/html", "text/plain", "application/json"] as const;
 // $ExpectType string[]
 negotiator.mediaTypes();
 negotiator.mediaTypes(availableMediaTypes);
@@ -21,7 +21,7 @@ negotiator.mediaTypes(availableMediaTypes);
 negotiator.mediaType();
 negotiator.mediaType(availableMediaTypes);
 
-const availableLanguages = ["en", "es", "fr"];
+const availableLanguages = ["en", "es", "fr"] as const;
 // $ExpectType string[]
 negotiator.languages();
 negotiator.languages(availableLanguages);
@@ -29,7 +29,7 @@ negotiator.languages(availableLanguages);
 negotiator.language();
 negotiator.language(availableLanguages);
 
-const availableCharsets = ["utf-8", "iso-8859-1", "iso-8859-5"];
+const availableCharsets = ["utf-8", "iso-8859-1", "iso-8859-5"] as const;
 // $ExpectType string[]
 negotiator.charsets();
 negotiator.charsets(availableCharsets);
@@ -37,7 +37,7 @@ negotiator.charsets(availableCharsets);
 negotiator.charset();
 negotiator.charset(availableCharsets);
 
-const availableEncodings = ["identity", "gzip"];
+const availableEncodings = ["identity", "gzip"] as const;
 // $ExpectType string[]
 negotiator.encodings();
 negotiator.encodings(availableEncodings);