diff --git a/src/builtins.ts b/src/builtins.ts
index 87069da616..d6e8120e3a 100644
--- a/src/builtins.ts
+++ b/src/builtins.ts
@@ -2673,14 +2673,14 @@ function builtin_atomic_cmpxchg(ctx: BuiltinContext): ExpressionRef {
 }
 builtins.set(BuiltinNames.atomic_cmpxchg, builtin_atomic_cmpxchg);
 
-// atomic.wait<T!>(ptr: usize, expected: T, timeout: i64) -> i32
+// atomic.wait<T!>(ptr: usize, expected: T, timeout?: i64) -> i32
 function builtin_atomic_wait(ctx: BuiltinContext): ExpressionRef {
   var compiler = ctx.compiler;
   var module = compiler.module;
   if (
     checkFeatureEnabled(ctx, Feature.THREADS) |
     checkTypeRequired(ctx) |
-    checkArgsRequired(ctx, 3)
+    checkArgsOptional(ctx, 2, 3)
   ) {
     compiler.currentType = Type.i32;
     return module.unreachable();
@@ -2690,7 +2690,9 @@ function builtin_atomic_wait(ctx: BuiltinContext): ExpressionRef {
   var type = typeArguments![0];
   var arg0 = compiler.compileExpression(operands[0], compiler.options.usizeType, Constraints.CONV_IMPLICIT);
   var arg1 = compiler.compileExpression(operands[1], type, Constraints.CONV_IMPLICIT);
-  var arg2 = compiler.compileExpression(operands[2], Type.i64, Constraints.CONV_IMPLICIT);
+  var arg2 = operands.length == 3
+    ? compiler.compileExpression(operands[2], Type.i64, Constraints.CONV_IMPLICIT)
+    : module.i64(-1, -1); // Infinite timeout
   compiler.currentType = Type.i32;
   switch (type.kind) {
     case TypeKind.I32:
@@ -2708,21 +2710,23 @@ function builtin_atomic_wait(ctx: BuiltinContext): ExpressionRef {
 }
 builtins.set(BuiltinNames.atomic_wait, builtin_atomic_wait);
 
-// atomic.notify(ptr: usize, count: i32) -> i32
+// atomic.notify(ptr: usize, count?: i32) -> i32
 function builtin_atomic_notify(ctx: BuiltinContext): ExpressionRef {
   var compiler = ctx.compiler;
   var module = compiler.module;
   if (
     checkFeatureEnabled(ctx, Feature.THREADS) |
     checkTypeAbsent(ctx) |
-    checkArgsRequired(ctx, 2)
+    checkArgsOptional(ctx, 1, 2)
   ) {
     compiler.currentType = Type.i32;
     return module.unreachable();
   }
   var operands = ctx.operands;
   var arg0 = compiler.compileExpression(operands[0], compiler.options.usizeType, Constraints.CONV_IMPLICIT);
-  var arg1 = compiler.compileExpression(operands[1], Type.i32, Constraints.CONV_IMPLICIT);
+  var arg1 = operands.length == 2
+    ? compiler.compileExpression(operands[1], Type.i32, Constraints.CONV_IMPLICIT)
+    : module.i32(-1); // Inifinity count of waiters
   compiler.currentType = Type.i32;
   return module.atomic_notify(arg0, arg1);
 }
diff --git a/std/assembly/index.d.ts b/std/assembly/index.d.ts
index e3989d3691..1f093996e7 100644
--- a/std/assembly/index.d.ts
+++ b/std/assembly/index.d.ts
@@ -252,9 +252,9 @@ declare namespace atomic {
   /** Atomically compares and exchanges an integer value in memory if the condition is met. */
   export function cmpxchg<T>(ptr: usize, expected: T, replacement: T, immOffset?: usize): T;
   /** Performs a wait operation on an address in memory suspending this agent if the integer condition is met. */
-  export function wait<T>(ptr: usize, expected: T, timeout: i64): AtomicWaitResult;
+  export function wait<T>(ptr: usize, expected: T, timeout?: i64): AtomicWaitResult;
   /** Performs a notify operation on an address in memory waking up suspended agents. */
-  export function notify(ptr: usize, count: i32): i32;
+  export function notify(ptr: usize, count?: i32): i32;
   /** Performs a fence operation, preserving synchronization guarantees of higher level languages. */
   export function fence(): void;
 }
@@ -345,7 +345,7 @@ declare namespace i32 {
     /** Atomically stores a 32-bit integer value to memory. */
     export function store(ptr: usize, value: i32, immOffset?: usize): void;
     /** Performs a wait operation on a 32-bit integer value in memory suspending this agent if the condition is met. */
-    export function wait(ptr: usize, expected: i32, timeout: i64): AtomicWaitResult;
+    export function wait(ptr: usize, expected: i32, timeout?: i64): AtomicWaitResult;
     /** Atomic 32-bit integer read-modify-write operations on 8-bit values. */
     export namespace rmw8 {
       /** Atomically adds an 8-bit unsigned integer value in memory. */
@@ -469,7 +469,7 @@ declare namespace i64 {
     /** Atomically stores a 64-bit integer value to memory. */
     export function store(ptr: usize, value: i64, immOffset?: usize): void;
     /** Performs a wait operation on a 64-bit integer value in memory suspending this agent if the condition is met. */
-    export function wait(ptr: usize, expected: i64, timeout: i64): AtomicWaitResult;
+    export function wait(ptr: usize, expected: i64, timeout?: i64): AtomicWaitResult;
     /** Atomic 64-bit integer read-modify-write operations on 8-bit values. */
     export namespace rmw8 {
       /** Atomically adds an 8-bit unsigned integer value in memory. */