diff --git a/src.ts/_admin/test-browser.ts b/src.ts/_admin/test-browser.ts
index 9828997c1..3f79c64b3 100644
--- a/src.ts/_admin/test-browser.ts
+++ b/src.ts/_admin/test-browser.ts
@@ -201,7 +201,7 @@ const TestData = (function() {
     return [ String(data.length), zlib.deflateRawSync(data).toString("base64") ].join(",");
   }
 
-  let data = [ ];
+  let data: Array<string> = [ ];
   data.push(`import { ethers } from "/index.js";`);
   data.push(`import { inflate } from "/static/tiny-inflate.js";`);
   data.push(`const fs = new Map();`);
diff --git a/src.ts/_tests/test-contract.ts b/src.ts/_tests/test-contract.ts
index 0e039b47f..2675a046a 100644
--- a/src.ts/_tests/test-contract.ts
+++ b/src.ts/_tests/test-contract.ts
@@ -249,7 +249,7 @@ describe("Test Typed Contract Interaction", function() {
         }
     ];
 
-    const abi = [ ];
+    const abi: Array<string> = [ ];
     for (let i = 1; i <= 32; i++) {
         abi.push(`function testTyped(uint${ i * 8 }) public pure returns (string memory)`);
         abi.push(`function testTyped(int${ i * 8 }) public pure returns (string memory)`);
diff --git a/src.ts/_tests/test-wallet-mnemonic.ts b/src.ts/_tests/test-wallet-mnemonic.ts
index 8d8e234f1..ae596c981 100644
--- a/src.ts/_tests/test-wallet-mnemonic.ts
+++ b/src.ts/_tests/test-wallet-mnemonic.ts
@@ -18,7 +18,7 @@ function fromHex(hex: string): string {
 }
 
 function repeat(text: string, length: number): Array<string> {
-    const result = [ ];
+    const result: Array<string> = [ ];
     while (result.length < length) { result.push(text); }
     return result;
 }
diff --git a/src.ts/abi/coders/abstract-coder.ts b/src.ts/abi/coders/abstract-coder.ts
index 8a4521a69..6e46e5ca1 100644
--- a/src.ts/abi/coders/abstract-coder.ts
+++ b/src.ts/abi/coders/abstract-coder.ts
@@ -182,7 +182,7 @@ export class Result extends Array<any> {
         }
         if (end > this.length) { end = this.length; }
 
-        const result = [ ], names = [ ];
+        const result: Array<any> = [ ], names: Array<null | string> = [ ];
         for (let i = start; i < end; i++) {
             result.push(this[i]);
             names.push(this.#names[i]);
@@ -195,7 +195,7 @@ export class Result extends Array<any> {
      *  @_ignore
      */
     filter(callback: (el: any, index: number, array: Result) => boolean, thisArg?: any): Result {
-        const result = [ ], names = [ ];
+        const result: Array<any> = [ ], names: Array<null | string> = [ ];
         for (let i = 0; i < this.length; i++) {
             const item = this[i];
             if (item instanceof Error) {
diff --git a/src.ts/abi/coders/array.ts b/src.ts/abi/coders/array.ts
index 3270713df..9323ed975 100644
--- a/src.ts/abi/coders/array.ts
+++ b/src.ts/abi/coders/array.ts
@@ -171,7 +171,7 @@ export class ArrayCoder extends Coder {
 
         assertArgumentCount(value.length, count, "coder array" + (this.localName? (" "+ this.localName): ""));
 
-        let coders = [];
+        let coders: Array<Coder> = [ ];
         for (let i = 0; i < value.length; i++) { coders.push(this.coder); }
 
         return pack(writer, coders, value);
@@ -190,7 +190,7 @@ export class ArrayCoder extends Coder {
             assert(count * WordSize <= reader.dataLength, "insufficient data length",
                 "BUFFER_OVERRUN", { buffer: reader.bytes, offset: count * WordSize, length: reader.dataLength });
         }
-        let coders = [];
+        let coders: Array<Coder> = [];
         for (let i = 0; i < count; i++) { coders.push(new AnonymousCoder(this.coder)); }
 
         return unpack(reader, coders);
diff --git a/src.ts/abi/fragments.ts b/src.ts/abi/fragments.ts
index c58f4fabc..b8a87b5c4 100644
--- a/src.ts/abi/fragments.ts
+++ b/src.ts/abi/fragments.ts
@@ -843,7 +843,7 @@ export class ParamType {
                 comps = null;
             }
 
-            let indexed = null;
+            let indexed: null | boolean = null;
             const keywords = consumeKeywords(obj, KwModifiers);
             if (keywords.has("indexed")) {
                 if (!allowIndexed) { throw new Error(""); }
@@ -1079,7 +1079,7 @@ export class ErrorFragment extends NamedFragment {
             });
         }
 
-        const result = [ ];
+        const result: Array<string> = [ ];
         if (format !== "sighash") { result.push("error"); }
         result.push(this.name + joinParams(format, this.inputs));
         return result.join(" ");
@@ -1154,7 +1154,7 @@ export class EventFragment extends NamedFragment {
             });
         }
 
-        const result = [ ];
+        const result: Array<string> = [ ];
         if (format !== "sighash") { result.push("event"); }
         result.push(this.name + joinParams(format, this.inputs));
         if (format !== "sighash" && this.anonymous) { result.push("anonymous"); }
@@ -1465,7 +1465,7 @@ export class FunctionFragment extends NamedFragment {
             });
         }
 
-        const result = [];
+        const result: Array<string> = [];
 
         if (format !== "sighash") { result.push("function"); }
 
diff --git a/src.ts/abi/interface.ts b/src.ts/abi/interface.ts
index 110f89ebf..e453f6ad5 100644
--- a/src.ts/abi/interface.ts
+++ b/src.ts/abi/interface.ts
@@ -595,7 +595,7 @@ export class Interface {
 
         // It is a bare name, look up the function (will return null if ambiguous)
         if (key.indexOf("(") === -1) {
-            const matching = [ ];
+            const matching: Array<EventFragment> = [ ];
             for (const [ name, fragment ] of this.#events) {
                 if (name.split("("/* fix:) */)[0] === key) { matching.push(fragment); }
             }
@@ -716,7 +716,7 @@ export class Interface {
 
         // It is a bare name, look up the function (will return null if ambiguous)
         if (key.indexOf("(") === -1) {
-            const matching = [ ];
+            const matching: Array<ErrorFragment> = [ ];
             for (const [ name, fragment ] of this.#errors) {
                 if (name.split("("/* fix:) */)[0] === key) { matching.push(fragment); }
             }
@@ -1154,7 +1154,7 @@ export class Interface {
         const keys: Array<null | string> = [ ];
         let nonIndexedIndex = 0, indexedIndex = 0;
         fragment.inputs.forEach((param, index) => {
-            let value = null;
+            let value: null | Indexed = null;
             if (param.indexed) {
                 if (resultIndexed == null) {
                     value = new Indexed(null);
diff --git a/src.ts/contract/contract.ts b/src.ts/contract/contract.ts
index 0c6e9d644..589536710 100644
--- a/src.ts/contract/contract.ts
+++ b/src.ts/contract/contract.ts
@@ -679,7 +679,7 @@ export class BaseContract implements Addressable, EventEmitterable<ContractEvent
         Object.defineProperty(this, internal, { value: { } });
 
         let addrPromise;
-        let addr = null;
+        let addr: null | string = null;
 
         let deployTx: null | ContractTransactionResponse = null;
         if (_deployTx) {
diff --git a/src.ts/providers/abstract-provider.ts b/src.ts/providers/abstract-provider.ts
index 2e6396775..deb59c182 100644
--- a/src.ts/providers/abstract-provider.ts
+++ b/src.ts/providers/abstract-provider.ts
@@ -907,7 +907,8 @@ export class AbstractProvider implements Provider {
                 })())
             });
 
-            let maxFeePerGas = null, maxPriorityFeePerGas = null;
+            let maxFeePerGas: null | bigint = null;
+            let maxPriorityFeePerGas: null | bigint = null;
 
             // These are the recommended EIP-1559 heuristics for fee data
             const block = this._wrapBlock(_block, network);
diff --git a/src.ts/providers/provider-fallback.ts b/src.ts/providers/provider-fallback.ts
index d9bea451b..f4952f4de 100644
--- a/src.ts/providers/provider-fallback.ts
+++ b/src.ts/providers/provider-fallback.ts
@@ -332,7 +332,7 @@ function getFuzzyMode(quorum: number, results: Array<TallyResult>): undefined |
     }
 
     let bestWeight = 0;
-    let bestResult = undefined;
+    let bestResult: undefined | number = undefined;
 
     for (const { weight, result } of tally.values()) {
         // Use this result, if this result meets quorum and has either:
diff --git a/src.ts/utils/rlp-decode.ts b/src.ts/utils/rlp-decode.ts
index acb3a21ad..330ba5cf9 100644
--- a/src.ts/utils/rlp-decode.ts
+++ b/src.ts/utils/rlp-decode.ts
@@ -27,7 +27,7 @@ type Decoded = {
 };
 
 function _decodeChildren(data: Uint8Array, offset: number, childOffset: number, length: number): Decoded {
-    const result = [];
+    const result: Array<any> = [];
 
     while (childOffset < offset + 1 + length) {
         const decoded = _decode(data, childOffset);
diff --git a/src.ts/utils/rlp-encode.ts b/src.ts/utils/rlp-encode.ts
index 9800e4b2f..a2cd0bcad 100644
--- a/src.ts/utils/rlp-encode.ts
+++ b/src.ts/utils/rlp-encode.ts
@@ -6,7 +6,7 @@ import type { RlpStructuredData } from "./rlp.js";
 
 
 function arrayifyInteger(value: number): Array<number> {
-    const result = [];
+    const result: Array<number> = [];
     while (value) {
         result.unshift(value & 0xff);
         value >>= 8;
diff --git a/src.ts/utils/utf8.ts b/src.ts/utils/utf8.ts
index 19cba00e7..0e893cd98 100644
--- a/src.ts/utils/utf8.ts
+++ b/src.ts/utils/utf8.ts
@@ -162,8 +162,8 @@ function getUtf8CodePoints(_bytes: BytesLike, onError?: Utf8ErrorFunc): Array<nu
         }
 
         // Multibyte; how many bytes left for this character?
-        let extraLength = null;
-        let overlongMask = null;
+        let extraLength: null | number = null;
+        let overlongMask: null | number = null;
 
         // 110x xxxx 10xx xxxx
         if ((c & 0xe0) === 0xc0) {
@@ -253,7 +253,7 @@ export function toUtf8Bytes(str: string, form?: UnicodeNormalizationForm): Uint8
         str = str.normalize(form);
     }
 
-    let result = [];
+    let result: Array<number> = [];
     for (let i = 0; i < str.length; i++) {
         const c = str.charCodeAt(i);
 
diff --git a/src.ts/wordlists/lang-ja.ts b/src.ts/wordlists/lang-ja.ts
index 7b1f2aaf3..e4b6cdce7 100644
--- a/src.ts/wordlists/lang-ja.ts
+++ b/src.ts/wordlists/lang-ja.ts
@@ -49,7 +49,7 @@ function toString(data: Array<number>): string {
 function loadWords(): Array<string> {
     if (_wordlist !== null) { return _wordlist; }
 
-    const wordlist = [];
+    const wordlist: Array<string> = [];
 
     // Transforms for normalizing (sort is a not quite UTF-8)
     const transform: { [key: string]: string | boolean } = {};
@@ -91,7 +91,7 @@ function loadWords(): Array<string> {
     for (let length = 3; length <= 9; length++) {
         const d = data[length - 3];
         for (let offset = 0; offset < d.length; offset += length) {
-            const word = [];
+            const word: Array<number> = [];
             for (let i = 0; i < length; i++) {
                  const k = mapping.indexOf(d[offset + i]);
                  word.push(227);
diff --git a/src.ts/wordlists/lang-zh.ts b/src.ts/wordlists/lang-zh.ts
index 048115bce..cd96f6937 100644
--- a/src.ts/wordlists/lang-zh.ts
+++ b/src.ts/wordlists/lang-zh.ts
@@ -24,7 +24,7 @@ const style = "~!@#$%^&*_-=[]{}|;:,.()<>?"
 function loadWords(locale: string): Array<string> {
     if (_wordlist[locale] != null) { return _wordlist[locale] as Array<string>; }
 
-    const wordlist = [];
+    const wordlist: Array<string> = [];
 
     let deltaOffset = 0;
     for (let i = 0; i < 2048; i++) {