diff --git a/src/resolver.ts b/src/resolver.ts
index 46d5d16570..1af41ba392 100644
--- a/src/resolver.ts
+++ b/src/resolver.ts
@@ -732,7 +732,12 @@ export class Resolver extends DiagnosticEmitter {
       // infer types with generic components while updating contextual types
       for (let i = 0; i < numParameters; ++i) {
         let argumentExpression = i < numArguments ? argumentNodes[i] : parameterNodes[i].initializer;
-        if (!argumentExpression) { // missing initializer -> too few arguments
+        if (!argumentExpression) {
+          // optional but not have initializer should be handled in the other place
+          if (parameterNodes[i].parameterKind == ParameterKind.OPTIONAL) {
+            continue;
+          }
+          // missing initializer -> too few arguments
           if (reportMode == ReportMode.REPORT) {
             this.error(
               DiagnosticCode.Expected_0_arguments_but_got_1,
diff --git a/tests/compiler/infer-generic.debug.wat b/tests/compiler/infer-generic.debug.wat
index 38de0bf265..1a6006328e 100644
--- a/tests/compiler/infer-generic.debug.wat
+++ b/tests/compiler/infer-generic.debug.wat
@@ -53,6 +53,7 @@
  (export "test2" (func $export:infer-generic/test2))
  (export "test3" (func $export:infer-generic/test3))
  (export "test4" (func $export:infer-generic/test4))
+ (export "inferAssert" (func $export:infer-generic/inferAssert))
  (start $~start)
  (func $infer-generic/inferCompatible<f64> (param $0 f64) (param $1 f64) (result i32)
   local.get $0
@@ -2233,6 +2234,24 @@
   local.get $0
   call $infer-generic/inferEncapsulatedFunctionMixed<f32,f64>
  )
+ (func $infer-generic/inferAssert (param $0 i32)
+  (local $1 i32)
+  local.get $0
+  local.tee $1
+  i32.eqz
+  if (result i32)
+   i32.const 0
+   i32.const 32
+   i32.const 67
+   i32.const 3
+   call $~lib/builtins/abort
+   unreachable
+  else
+   local.get $1
+  end
+  i32.load
+  drop
+ )
  (func $~lib/rt/__visit_globals (param $0 i32)
   (local $1 i32)
   global.get $infer-generic/arr
@@ -2421,7 +2440,7 @@
   if
    i32.const 0
    i32.const 32
-   i32.const 60
+   i32.const 62
    i32.const 1
    call $~lib/builtins/abort
    unreachable
@@ -2464,7 +2483,7 @@
   if
    i32.const 0
    i32.const 32
-   i32.const 61
+   i32.const 63
    i32.const 1
    call $~lib/builtins/abort
    unreachable
@@ -2562,4 +2581,20 @@
   global.set $~lib/memory/__stack_pointer
   local.get $1
  )
+ (func $export:infer-generic/inferAssert (param $0 i32)
+  global.get $~lib/memory/__stack_pointer
+  i32.const 4
+  i32.sub
+  global.set $~lib/memory/__stack_pointer
+  call $~stack_check
+  global.get $~lib/memory/__stack_pointer
+  local.get $0
+  i32.store
+  local.get $0
+  call $infer-generic/inferAssert
+  global.get $~lib/memory/__stack_pointer
+  i32.const 4
+  i32.add
+  global.set $~lib/memory/__stack_pointer
+ )
 )
diff --git a/tests/compiler/infer-generic.release.wat b/tests/compiler/infer-generic.release.wat
index 6279d2b748..b1e303a597 100644
--- a/tests/compiler/infer-generic.release.wat
+++ b/tests/compiler/infer-generic.release.wat
@@ -1,10 +1,10 @@
 (module
  (type $none_=>_none (func))
+ (type $i32_=>_none (func (param i32)))
  (type $i32_f32_i32_i32_=>_i32 (func (param i32 f32 i32 i32) (result i32)))
  (type $i32_i32_=>_none (func (param i32 i32)))
  (type $none_=>_i32 (func (result i32)))
  (type $i32_=>_i32 (func (param i32) (result i32)))
- (type $i32_=>_none (func (param i32)))
  (type $i32_i32_i32_i32_=>_none (func (param i32 i32 i32 i32)))
  (type $i32_i32_i32_=>_none (func (param i32 i32 i32)))
  (type $f32_=>_f32 (func (param f32) (result f32)))
@@ -49,6 +49,7 @@
  (export "test2" (func $export:infer-generic/test2))
  (export "test3" (func $export:infer-generic/test2))
  (export "test4" (func $export:infer-generic/test2))
+ (export "inferAssert" (func $export:infer-generic/inferAssert))
  (start $~start)
  (func $start:infer-generic~anonymous|0 (param $0 i32) (param $1 f32) (param $2 i32) (param $3 i32) (result i32)
   local.get $1
@@ -1458,6 +1459,43 @@
   global.set $~lib/memory/__stack_pointer
   local.get $0
  )
+ (func $export:infer-generic/inferAssert (param $0 i32)
+  global.get $~lib/memory/__stack_pointer
+  i32.const 4
+  i32.sub
+  global.set $~lib/memory/__stack_pointer
+  global.get $~lib/memory/__stack_pointer
+  i32.const 1684
+  i32.lt_s
+  if
+   i32.const 18096
+   i32.const 18144
+   i32.const 1
+   i32.const 1
+   call $~lib/builtins/abort
+   unreachable
+  end
+  global.get $~lib/memory/__stack_pointer
+  local.get $0
+  i32.store
+  local.get $0
+  i32.eqz
+  if
+   i32.const 0
+   i32.const 1056
+   i32.const 67
+   i32.const 3
+   call $~lib/builtins/abort
+   unreachable
+  end
+  local.get $0
+  i32.load
+  drop
+  global.get $~lib/memory/__stack_pointer
+  i32.const 4
+  i32.add
+  global.set $~lib/memory/__stack_pointer
+ )
  (func $byn-split-outlined-A$~lib/rt/itcms/__visit (param $0 i32)
   (local $1 i32)
   (local $2 i32)
diff --git a/tests/compiler/infer-generic.ts b/tests/compiler/infer-generic.ts
index 9df90f9147..d61fac1463 100644
--- a/tests/compiler/infer-generic.ts
+++ b/tests/compiler/infer-generic.ts
@@ -20,7 +20,7 @@ export function test2(arr: f32[]): f32[] {
 
 // (a: T) => R should infer T,R
 
-function inferEncapsulatedFunction<T,R>(fn: (a: T) => R): (a: T) => R {
+function inferEncapsulatedFunction<T, R>(fn: (a: T) => R): (a: T) => R {
   return fn;
 }
 
@@ -30,7 +30,7 @@ export function test3(fn: (a: f32) => f64): (a: f32) => f64 {
 
 // (a: T, b: i32) => R should not bail out on non-inferred i32
 
-function inferEncapsulatedFunctionMixed<T,R>(fn: (a: T, b: i32) => R): (a: T, b: i32) => R {
+function inferEncapsulatedFunctionMixed<T, R>(fn: (a: T, b: i32) => R): (a: T, b: i32) => R {
   return fn;
 }
 
@@ -53,9 +53,16 @@ arr.reduce(((acc, cur) => acc && cur != 0), false);
 
 // should fall back to default type
 
-class Ref { x: i32; }
+class Ref {
+  x: i32;
+}
 function inferDefault<T = Ref>(a: T): T {
   return a;
 }
 assert(inferDefault(1) == 1);
 assert(inferDefault({ x: 2 }) instanceof Ref);
+
+// infer builtin assert generic
+export function inferAssert(v: Ref | null): void {
+  assert(v).x;
+}