diff --git a/src/resolver.ts b/src/resolver.ts
index 5a19f8e152..6689c88add 100644
--- a/src/resolver.ts
+++ b/src/resolver.ts
@@ -763,7 +763,14 @@ export class Resolver extends DiagnosticEmitter {
           }
           let defaultType = typeParameterNode.defaultType;
           if (defaultType) {
-            let resolvedDefaultType = this.resolveType(defaultType, ctxFlow.actualFunction, contextualTypeArguments, reportMode);
+            // Default parameters are resolved in context of the called function, not the calling function
+            let defaultTypeContextualTypeArguments: Map<string, Type> | null = null;
+            if (prototype.parent.kind == ElementKind.CLASS) {
+              defaultTypeContextualTypeArguments = (<Class>prototype.parent).contextualTypeArguments;
+            } else if (prototype.parent.kind == ElementKind.FUNCTION) {
+              defaultTypeContextualTypeArguments = (<Function>prototype.parent).contextualTypeArguments;
+            }
+            let resolvedDefaultType = this.resolveType(defaultType, prototype, defaultTypeContextualTypeArguments, reportMode);
             if (!resolvedDefaultType) return null;
             resolvedTypeArguments[i] = resolvedDefaultType;
             continue;
diff --git a/tests/compiler/optional-typeparameters.debug.wat b/tests/compiler/optional-typeparameters.debug.wat
index efbf0b9585..cbe085dc33 100644
--- a/tests/compiler/optional-typeparameters.debug.wat
+++ b/tests/compiler/optional-typeparameters.debug.wat
@@ -26,10 +26,12 @@
  (global $~lib/native/ASC_LOW_MEMORY_LIMIT i32 (i32.const 0))
  (global $optional-typeparameters/tConcrete (mut i32) (i32.const 0))
  (global $optional-typeparameters/tDerived (mut i32) (i32.const 0))
+ (global $optional-typeparameters/tMethodDerived (mut i32) (i32.const 0))
+ (global $optional-typeparameters/tMethodDerived2 (mut i32) (i32.const 0))
  (global $~lib/rt/__rtti_base i32 (i32.const 416))
- (global $~lib/memory/__data_end i32 (i32.const 460))
- (global $~lib/memory/__stack_pointer (mut i32) (i32.const 16844))
- (global $~lib/memory/__heap_base i32 (i32.const 16844))
+ (global $~lib/memory/__data_end i32 (i32.const 484))
+ (global $~lib/memory/__stack_pointer (mut i32) (i32.const 16868))
+ (global $~lib/memory/__heap_base i32 (i32.const 16868))
  (memory $0 1)
  (data (i32.const 12) "<\00\00\00\00\00\00\00\00\00\00\00\01\00\00\00(\00\00\00A\00l\00l\00o\00c\00a\00t\00i\00o\00n\00 \00t\00o\00o\00 \00l\00a\00r\00g\00e\00\00\00\00\00")
  (data (i32.const 76) "<\00\00\00\00\00\00\00\00\00\00\00\01\00\00\00 \00\00\00~\00l\00i\00b\00/\00r\00t\00/\00i\00t\00c\00m\00s\00.\00t\00s\00\00\00\00\00\00\00\00\00\00\00\00\00")
@@ -39,7 +41,7 @@
  (data (i32.const 268) ",\00\00\00\00\00\00\00\00\00\00\00\01\00\00\00\14\00\00\00~\00l\00i\00b\00/\00r\00t\00.\00t\00s\00\00\00\00\00\00\00\00\00")
  (data (i32.const 320) "\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00")
  (data (i32.const 348) "<\00\00\00\00\00\00\00\00\00\00\00\01\00\00\00\1e\00\00\00~\00l\00i\00b\00/\00r\00t\00/\00t\00l\00s\00f\00.\00t\00s\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00")
- (data (i32.const 416) "\05\00\00\00 \00\00\00\00\00\00\00 \00\00\00\00\00\00\00\00\00\00\00\00\00\00\00 \00\00\00\00\00\00\00 \00\00\00\00\00\00\00")
+ (data (i32.const 416) "\08\00\00\00 \00\00\00\00\00\00\00 \00\00\00\00\00\00\00\00\00\00\00\00\00\00\00 \00\00\00\00\00\00\00 \00\00\00\00\00\00\00 \00\00\00\00\00\00\00\02A\00\00\00\00\00\00 \00\00\00\00\00\00\00")
  (table $0 1 1 funcref)
  (elem $0 (i32.const 1))
  (export "memory" (memory $0))
@@ -2132,6 +2134,16 @@
   local.get $b
   f64.add
  )
+ (func $optional-typeparameters/TestMethodDerived<~lib/string/String>#test<~lib/array/Array<~lib/string/String>> (param $this i32)
+  i32.const 6
+  i32.const 6
+  i32.eq
+  drop
+ )
+ (func $optional-typeparameters/TestMethodDerived2<f64>#foo (param $this i32) (param $v i32)
+  local.get $v
+  call $optional-typeparameters/TestMethodDerived<~lib/string/String>#test<~lib/array/Array<~lib/string/String>>
+ )
  (func $~lib/rt/__visit_globals (param $0 i32)
   (local $1 i32)
   global.get $optional-typeparameters/tConcrete
@@ -2148,6 +2160,20 @@
    local.get $0
    call $~lib/rt/itcms/__visit
   end
+  global.get $optional-typeparameters/tMethodDerived
+  local.tee $1
+  if
+   local.get $1
+   local.get $0
+   call $~lib/rt/itcms/__visit
+  end
+  global.get $optional-typeparameters/tMethodDerived2
+  local.tee $1
+  if
+   local.get $1
+   local.get $0
+   call $~lib/rt/itcms/__visit
+  end
   i32.const 224
   local.get $0
   call $~lib/rt/itcms/__visit
@@ -2166,28 +2192,90 @@
    call $~lib/rt/itcms/__visit
   end
  )
+ (func $~lib/array/Array<~lib/string/String>#__visit (param $this i32) (param $cookie i32)
+  (local $var$2 i32)
+  (local $var$3 i32)
+  (local $var$4 i32)
+  (local $val i32)
+  i32.const 1
+  drop
+  local.get $this
+  i32.load offset=4
+  local.set $var$2
+  local.get $var$2
+  local.get $this
+  i32.load offset=12
+  i32.const 2
+  i32.shl
+  i32.add
+  local.set $var$3
+  loop $while-continue|0
+   local.get $var$2
+   local.get $var$3
+   i32.lt_u
+   local.set $var$4
+   local.get $var$4
+   if
+    local.get $var$2
+    i32.load
+    local.set $val
+    local.get $val
+    if
+     local.get $val
+     local.get $cookie
+     call $~lib/rt/itcms/__visit
+    end
+    local.get $var$2
+    i32.const 4
+    i32.add
+    local.set $var$2
+    br $while-continue|0
+   end
+  end
+  local.get $this
+  i32.load
+  local.get $cookie
+  call $~lib/rt/itcms/__visit
+ )
+ (func $~lib/array/Array<~lib/string/String>~visit (param $0 i32) (param $1 i32)
+  local.get $0
+  local.get $1
+  call $~lib/array/Array<~lib/string/String>#__visit
+ )
  (func $~lib/rt/__visit_members (param $0 i32) (param $1 i32)
   block $invalid
-   block $optional-typeparameters/TestDerived<f64,f64>
-    block $optional-typeparameters/TestConcrete<i32,i32>
-     block $~lib/arraybuffer/ArrayBufferView
-      block $~lib/string/String
-       block $~lib/arraybuffer/ArrayBuffer
+   block $optional-typeparameters/TestMethodDerived2<f64>
+    block $~lib/array/Array<~lib/string/String>
+     block $optional-typeparameters/TestMethodDerived<~lib/string/String>
+      block $optional-typeparameters/TestDerived<f64,f64>
+       block $optional-typeparameters/TestConcrete<i32,i32>
+        block $~lib/arraybuffer/ArrayBufferView
+         block $~lib/string/String
+          block $~lib/arraybuffer/ArrayBuffer
+           local.get $0
+           i32.const 8
+           i32.sub
+           i32.load
+           br_table $~lib/arraybuffer/ArrayBuffer $~lib/string/String $~lib/arraybuffer/ArrayBufferView $optional-typeparameters/TestConcrete<i32,i32> $optional-typeparameters/TestDerived<f64,f64> $optional-typeparameters/TestMethodDerived<~lib/string/String> $~lib/array/Array<~lib/string/String> $optional-typeparameters/TestMethodDerived2<f64> $invalid
+          end
+          return
+         end
+         return
+        end
         local.get $0
-        i32.const 8
-        i32.sub
-        i32.load
-        br_table $~lib/arraybuffer/ArrayBuffer $~lib/string/String $~lib/arraybuffer/ArrayBufferView $optional-typeparameters/TestConcrete<i32,i32> $optional-typeparameters/TestDerived<f64,f64> $invalid
+        local.get $1
+        call $~lib/arraybuffer/ArrayBufferView~visit
+        return
        end
        return
       end
       return
      end
-     local.get $0
-     local.get $1
-     call $~lib/arraybuffer/ArrayBufferView~visit
      return
     end
+    local.get $0
+    local.get $1
+    call $~lib/array/Array<~lib/string/String>~visit
     return
    end
    return
@@ -2202,8 +2290,8 @@
   global.get $~lib/memory/__data_end
   i32.lt_s
   if
-   i32.const 16864
-   i32.const 16912
+   i32.const 16896
+   i32.const 16944
    i32.const 1
    i32.const 1
    call $~lib/builtins/abort
@@ -2213,13 +2301,13 @@
  (func $start:optional-typeparameters
   (local $0 i32)
   global.get $~lib/memory/__stack_pointer
-  i32.const 4
+  i32.const 8
   i32.sub
   global.set $~lib/memory/__stack_pointer
   call $~stack_check
   global.get $~lib/memory/__stack_pointer
-  i32.const 0
-  i32.store
+  i64.const 0
+  i64.store
   i32.const 1
   call $optional-typeparameters/testConcrete<i32,i32>
   drop
@@ -2269,8 +2357,34 @@
   f64.const 2
   call $optional-typeparameters/TestDerived<f64,f64>#test<f64>
   drop
+  i32.const 0
+  call $optional-typeparameters/TestMethodDerived<~lib/string/String>#constructor
+  global.set $optional-typeparameters/tMethodDerived
+  global.get $optional-typeparameters/tMethodDerived
+  local.set $0
   global.get $~lib/memory/__stack_pointer
-  i32.const 4
+  local.get $0
+  i32.store
+  local.get $0
+  call $optional-typeparameters/TestMethodDerived<~lib/string/String>#test<~lib/array/Array<~lib/string/String>>
+  i32.const 0
+  call $optional-typeparameters/TestMethodDerived2<f64>#constructor
+  global.set $optional-typeparameters/tMethodDerived2
+  global.get $optional-typeparameters/tMethodDerived2
+  local.set $0
+  global.get $~lib/memory/__stack_pointer
+  local.get $0
+  i32.store
+  local.get $0
+  global.get $optional-typeparameters/tMethodDerived
+  local.set $0
+  global.get $~lib/memory/__stack_pointer
+  local.get $0
+  i32.store offset=4
+  local.get $0
+  call $optional-typeparameters/TestMethodDerived2<f64>#foo
+  global.get $~lib/memory/__stack_pointer
+  i32.const 8
   i32.add
   global.set $~lib/memory/__stack_pointer
  )
@@ -2330,4 +2444,60 @@
   global.set $~lib/memory/__stack_pointer
   local.get $1
  )
+ (func $optional-typeparameters/TestMethodDerived<~lib/string/String>#constructor (param $0 i32) (result i32)
+  (local $1 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
+  i32.const 0
+  i32.store
+  local.get $0
+  i32.eqz
+  if
+   global.get $~lib/memory/__stack_pointer
+   i32.const 0
+   i32.const 5
+   call $~lib/rt/itcms/__new
+   local.tee $0
+   i32.store
+  end
+  local.get $0
+  local.set $1
+  global.get $~lib/memory/__stack_pointer
+  i32.const 4
+  i32.add
+  global.set $~lib/memory/__stack_pointer
+  local.get $1
+ )
+ (func $optional-typeparameters/TestMethodDerived2<f64>#constructor (param $0 i32) (result i32)
+  (local $1 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
+  i32.const 0
+  i32.store
+  local.get $0
+  i32.eqz
+  if
+   global.get $~lib/memory/__stack_pointer
+   i32.const 0
+   i32.const 7
+   call $~lib/rt/itcms/__new
+   local.tee $0
+   i32.store
+  end
+  local.get $0
+  local.set $1
+  global.get $~lib/memory/__stack_pointer
+  i32.const 4
+  i32.add
+  global.set $~lib/memory/__stack_pointer
+  local.get $1
+ )
 )
diff --git a/tests/compiler/optional-typeparameters.release.wat b/tests/compiler/optional-typeparameters.release.wat
index ddb8d5a540..f8d4bdf5dd 100644
--- a/tests/compiler/optional-typeparameters.release.wat
+++ b/tests/compiler/optional-typeparameters.release.wat
@@ -19,7 +19,9 @@
  (global $~lib/rt/tlsf/ROOT (mut i32) (i32.const 0))
  (global $optional-typeparameters/tConcrete (mut i32) (i32.const 0))
  (global $optional-typeparameters/tDerived (mut i32) (i32.const 0))
- (global $~lib/memory/__stack_pointer (mut i32) (i32.const 17868))
+ (global $optional-typeparameters/tMethodDerived (mut i32) (i32.const 0))
+ (global $optional-typeparameters/tMethodDerived2 (mut i32) (i32.const 0))
+ (global $~lib/memory/__stack_pointer (mut i32) (i32.const 17892))
  (memory $0 1)
  (data (i32.const 1036) "<")
  (data (i32.const 1048) "\01\00\00\00(\00\00\00A\00l\00l\00o\00c\00a\00t\00i\00o\00n\00 \00t\00o\00o\00 \00l\00a\00r\00g\00e")
@@ -31,8 +33,8 @@
  (data (i32.const 1304) "\01\00\00\00\14\00\00\00~\00l\00i\00b\00/\00r\00t\00.\00t\00s")
  (data (i32.const 1372) "<")
  (data (i32.const 1384) "\01\00\00\00\1e\00\00\00~\00l\00i\00b\00/\00r\00t\00/\00t\00l\00s\00f\00.\00t\00s")
- (data (i32.const 1440) "\05\00\00\00 \00\00\00\00\00\00\00 ")
- (data (i32.const 1468) " \00\00\00\00\00\00\00 ")
+ (data (i32.const 1440) "\08\00\00\00 \00\00\00\00\00\00\00 ")
+ (data (i32.const 1468) " \00\00\00\00\00\00\00 \00\00\00\00\00\00\00 \00\00\00\00\00\00\00\02A\00\00\00\00\00\00 ")
  (export "memory" (memory $0))
  (start $~start)
  (func $~lib/rt/itcms/visitRoots
@@ -50,6 +52,18 @@
    local.get $0
    call $byn-split-outlined-A$~lib/rt/itcms/__visit
   end
+  global.get $optional-typeparameters/tMethodDerived
+  local.tee $0
+  if
+   local.get $0
+   call $byn-split-outlined-A$~lib/rt/itcms/__visit
+  end
+  global.get $optional-typeparameters/tMethodDerived2
+  local.tee $0
+  if
+   local.get $0
+   call $byn-split-outlined-A$~lib/rt/itcms/__visit
+  end
   i32.const 1248
   call $byn-split-outlined-A$~lib/rt/itcms/__visit
   i32.const 1056
@@ -623,10 +637,10 @@
   if
    unreachable
   end
-  i32.const 17872
+  i32.const 17904
   i32.const 0
   i32.store
-  i32.const 19440
+  i32.const 19472
   i32.const 0
   i32.store
   loop $for-loop|0
@@ -637,7 +651,7 @@
     local.get $0
     i32.const 2
     i32.shl
-    i32.const 17872
+    i32.const 17904
     i32.add
     i32.const 0
     i32.store offset=4
@@ -655,7 +669,7 @@
       i32.add
       i32.const 2
       i32.shl
-      i32.const 17872
+      i32.const 17904
       i32.add
       i32.const 0
       i32.store offset=96
@@ -673,13 +687,13 @@
     br $for-loop|0
    end
   end
-  i32.const 17872
-  i32.const 19444
+  i32.const 17904
+  i32.const 19476
   memory.size
   i32.const 16
   i32.shl
   call $~lib/rt/tlsf/addMemory
-  i32.const 17872
+  i32.const 17904
   global.set $~lib/rt/tlsf/ROOT
  )
  (func $~lib/rt/itcms/step (result i32)
@@ -764,7 +778,7 @@
      local.set $0
      loop $while-continue|0
       local.get $0
-      i32.const 17868
+      i32.const 17892
       i32.lt_u
       if
        local.get $0
@@ -864,7 +878,7 @@
      unreachable
     end
     local.get $0
-    i32.const 17868
+    i32.const 17892
     i32.lt_u
     if
      local.get $0
@@ -887,7 +901,7 @@
      i32.const 4
      i32.add
      local.tee $0
-     i32.const 17868
+     i32.const 17892
      i32.ge_u
      if
       global.get $~lib/rt/tlsf/ROOT
@@ -1240,56 +1254,95 @@
   local.get $0
  )
  (func $~lib/rt/__visit_members (param $0 i32)
-  block $invalid
-   block $optional-typeparameters/TestDerived<f64,f64>
-    block $optional-typeparameters/TestConcrete<i32,i32>
-     block $~lib/arraybuffer/ArrayBufferView
-      block $~lib/string/String
-       block $~lib/arraybuffer/ArrayBuffer
-        local.get $0
-        i32.const 8
-        i32.sub
-        i32.load
-        br_table $~lib/arraybuffer/ArrayBuffer $~lib/string/String $~lib/arraybuffer/ArrayBufferView $optional-typeparameters/TestConcrete<i32,i32> $optional-typeparameters/TestDerived<f64,f64> $invalid
+  (local $1 i32)
+  (local $2 i32)
+  (local $3 i32)
+  block $folding-inner0
+   block $invalid
+    block $optional-typeparameters/TestMethodDerived2<f64>
+     block $~lib/array/Array<~lib/string/String>
+      block $optional-typeparameters/TestMethodDerived<~lib/string/String>
+       block $optional-typeparameters/TestDerived<f64,f64>
+        block $optional-typeparameters/TestConcrete<i32,i32>
+         block $~lib/string/String
+          block $~lib/arraybuffer/ArrayBuffer
+           local.get $0
+           i32.const 8
+           i32.sub
+           i32.load
+           br_table $~lib/arraybuffer/ArrayBuffer $~lib/string/String $folding-inner0 $optional-typeparameters/TestConcrete<i32,i32> $optional-typeparameters/TestDerived<f64,f64> $optional-typeparameters/TestMethodDerived<~lib/string/String> $~lib/array/Array<~lib/string/String> $optional-typeparameters/TestMethodDerived2<f64> $invalid
+          end
+          return
+         end
+         return
+        end
+        return
        end
        return
       end
       return
      end
      local.get $0
-     i32.load
-     local.tee $0
-     if
-      local.get $0
-      call $byn-split-outlined-A$~lib/rt/itcms/__visit
+     i32.load offset=4
+     local.tee $1
+     local.get $0
+     i32.load offset=12
+     i32.const 2
+     i32.shl
+     i32.add
+     local.set $3
+     loop $while-continue|0
+      local.get $1
+      local.get $3
+      i32.lt_u
+      if
+       local.get $1
+       i32.load
+       local.tee $2
+       if
+        local.get $2
+        call $byn-split-outlined-A$~lib/rt/itcms/__visit
+       end
+       local.get $1
+       i32.const 4
+       i32.add
+       local.set $1
+       br $while-continue|0
+      end
      end
-     return
+     br $folding-inner0
     end
     return
    end
-   return
+   unreachable
+  end
+  local.get $0
+  i32.load
+  local.tee $0
+  if
+   local.get $0
+   call $byn-split-outlined-A$~lib/rt/itcms/__visit
   end
-  unreachable
  )
  (func $~start
   (local $0 i32)
   global.get $~lib/memory/__stack_pointer
-  i32.const 4
+  i32.const 8
   i32.sub
   global.set $~lib/memory/__stack_pointer
   block $folding-inner0
    global.get $~lib/memory/__stack_pointer
-   i32.const 1484
+   i32.const 1508
    i32.lt_s
    br_if $folding-inner0
    global.get $~lib/memory/__stack_pointer
    local.tee $0
-   i32.const 0
-   i32.store
+   i64.const 0
+   i64.store
    memory.size
    i32.const 16
    i32.shl
-   i32.const 17868
+   i32.const 17892
    i32.sub
    i32.const 1
    i32.shr_u
@@ -1323,7 +1376,7 @@
    i32.sub
    global.set $~lib/memory/__stack_pointer
    global.get $~lib/memory/__stack_pointer
-   i32.const 1484
+   i32.const 1508
    i32.lt_s
    br_if $folding-inner0
    global.get $~lib/memory/__stack_pointer
@@ -1349,7 +1402,7 @@
    i32.sub
    global.set $~lib/memory/__stack_pointer
    global.get $~lib/memory/__stack_pointer
-   i32.const 1484
+   i32.const 1508
    i32.lt_s
    br_if $folding-inner0
    global.get $~lib/memory/__stack_pointer
@@ -1372,12 +1425,67 @@
    i32.store
    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 1508
+   i32.lt_s
+   br_if $folding-inner0
+   global.get $~lib/memory/__stack_pointer
+   local.tee $0
+   i32.const 0
+   i32.store
+   local.get $0
+   i32.const 5
+   call $~lib/rt/itcms/__new
+   local.tee $0
+   i32.store
+   global.get $~lib/memory/__stack_pointer
+   i32.const 4
+   i32.add
+   global.set $~lib/memory/__stack_pointer
+   local.get $0
+   global.set $optional-typeparameters/tMethodDerived
+   global.get $~lib/memory/__stack_pointer
+   global.get $optional-typeparameters/tMethodDerived
+   i32.store
+   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 1508
+   i32.lt_s
+   br_if $folding-inner0
+   global.get $~lib/memory/__stack_pointer
+   local.tee $0
+   i32.const 0
+   i32.store
+   local.get $0
+   i32.const 7
+   call $~lib/rt/itcms/__new
+   local.tee $0
+   i32.store
+   global.get $~lib/memory/__stack_pointer
+   i32.const 4
+   i32.add
+   global.set $~lib/memory/__stack_pointer
+   local.get $0
+   global.set $optional-typeparameters/tMethodDerived2
+   global.get $~lib/memory/__stack_pointer
+   global.get $optional-typeparameters/tMethodDerived2
+   i32.store
+   global.get $~lib/memory/__stack_pointer
+   global.get $optional-typeparameters/tMethodDerived
+   i32.store offset=4
+   global.get $~lib/memory/__stack_pointer
+   i32.const 8
    i32.add
    global.set $~lib/memory/__stack_pointer
    return
   end
-  i32.const 17888
-  i32.const 17936
+  i32.const 17920
+  i32.const 17968
   i32.const 1
   i32.const 1
   call $~lib/builtins/abort
@@ -1426,7 +1534,7 @@
     if
      i32.const 0
      local.get $1
-     i32.const 17868
+     i32.const 17892
      i32.lt_u
      local.get $1
      i32.load offset=8
diff --git a/tests/compiler/optional-typeparameters.ts b/tests/compiler/optional-typeparameters.ts
index a726b28f4a..7ba1699c0e 100644
--- a/tests/compiler/optional-typeparameters.ts
+++ b/tests/compiler/optional-typeparameters.ts
@@ -1,21 +1,21 @@
-function testConcrete<T,U = i32>(a: T): U {
+function testConcrete<T, U = i32>(a: T): U {
   return a;
 }
 
-function testDerived<T,U = T>(a: T): U {
+function testDerived<T, U = T>(a: T): U {
   return a;
 }
 
 testConcrete<i32>(1);
 testDerived<i32>(2);
 
-class TestConcrete<T,U = i32> {
+class TestConcrete<T, U = i32> {
   test<V = i32>(a: T, b: U): V {
     return a + b;
   }
 }
 
-class TestDerived<T,U = T> {
+class TestDerived<T, U = T> {
   test<V = U>(a: T, b: U): V {
     return a + b;
   }
@@ -25,3 +25,19 @@ var tConcrete = new TestConcrete<i32>();
 tConcrete.test<i32>(1, 2);
 var tDerived = new TestDerived<f64>();
 tDerived.test<f64>(1, 2);
+
+class TestMethodDerived<T> {
+  test<U = T[]>(): void {
+    assert(idof<U>() == idof<T[]>());
+  }
+}
+class TestMethodDerived2<T> {
+  foo(v: TestMethodDerived<string>): void {
+    v.test();
+  }
+}
+
+var tMethodDerived = new TestMethodDerived<string>();
+tMethodDerived.test();
+var tMethodDerived2 = new TestMethodDerived2<f64>();
+tMethodDerived2.foo(tMethodDerived);