diff --git a/test/chancap.go b/test/chancap.go
index b3e4023..b08478a 100644
--- a/test/chancap.go
+++ b/test/chancap.go
@@ -8,8 +8,17 @@
 
 package main
 
+import (
+	"strings"
+	"unsafe"
+)
+
+type T chan int
+
+const ptrSize = unsafe.Sizeof((*byte)(nil))
+
 func main() {
-	c := make(chan int, 10)
+	c := make(T, 10)
 	if len(c) != 0 || cap(c) != 10 {
 		println("chan len/cap ", len(c), cap(c), " want 0 10")
 		panic("fail")
@@ -23,9 +32,39 @@
 		panic("fail")
 	}
 
-	c = make(chan int)
+	c = make(T)
 	if len(c) != 0 || cap(c) != 0 {
 		println("chan len/cap ", len(c), cap(c), " want 0 0")
 		panic("fail")
 	}
+
+	n := -1
+	shouldPanic("makechan: size out of range", func() { _ = make(T, n) })
+	shouldPanic("makechan: size out of range", func() { _ = make(T, int64(n)) })
+	if ptrSize == 8 {
+		n = 1 << 20
+		n <<= 20
+		shouldPanic("makechan: size out of range", func() { _ = make(T, n) })
+		n <<= 20
+		shouldPanic("makechan: size out of range", func() { _ = make(T, n) })
+	} else {
+		n = 1<<31 - 1
+		shouldPanic("makechan: size out of range", func() { _ = make(T, n) })
+		shouldPanic("makechan: size out of range", func() { _ = make(T, int64(n)) })
+	}
+}
+
+func shouldPanic(str string, f func()) {
+	defer func() {
+		err := recover()
+		if err == nil {
+			panic("did not panic")
+		}
+		s := err.(error).Error()
+		if !strings.Contains(s, str) {
+			panic("got panic " + s + ", want " + str)
+		}
+	}()
+
+	f()
 }