diff --git a/cl/_testgo/makeslice/in.go b/cl/_testgo/makeslice/in.go
new file mode 100644
index 00000000..d6602a8c
--- /dev/null
+++ b/cl/_testgo/makeslice/in.go
@@ -0,0 +1,56 @@
+package main
+
+func main() {
+}
+
+func init() {
+	var n int = 2
+	buf := make([]int, n, n*2)
+	if len(buf) != 2 || cap(buf) != 4 {
+		panic("error")
+	}
+}
+
+func init() {
+	var n int32 = 2
+	buf := make([]int, n, n*2)
+	if len(buf) != 2 || cap(buf) != 4 {
+		panic("error")
+	}
+}
+
+func init() {
+	defer func() {
+		r := recover()
+		if r == nil {
+			println("must error")
+		}
+	}()
+	var n int = -1
+	buf := make([]int, n)
+	_ = buf
+}
+
+func init() {
+	defer func() {
+		r := recover()
+		if r == nil {
+			println("must error")
+		}
+	}()
+	var n int = 2
+	buf := make([]int, n, n-1)
+	_ = buf
+}
+
+func init() {
+	defer func() {
+		r := recover()
+		if r == nil {
+			println("must error")
+		}
+	}()
+	var n int64 = 1<<63 - 1
+	buf := make([]int, n)
+	_ = buf
+}
diff --git a/cl/_testgo/makeslice/out.ll b/cl/_testgo/makeslice/out.ll
new file mode 100644
index 00000000..1c8a0e79
--- /dev/null
+++ b/cl/_testgo/makeslice/out.ll
@@ -0,0 +1 @@
+;
\ No newline at end of file
diff --git a/cl/_testgo/tprecur/out.ll b/cl/_testgo/tprecur/out.ll
index a1e869f6..6cd1f48f 100644
--- a/cl/_testgo/tprecur/out.ll
+++ b/cl/_testgo/tprecur/out.ll
@@ -108,67 +108,58 @@ declare void @"github.com/goplus/llgo/internal/runtime.Panic"(%"github.com/goplu
 
 define i64 @"main.recur2[main.T]"(i64 %0) {
 _llgo_0:
-  %1 = mul i64 %0, 8
-  %2 = call ptr @"github.com/goplus/llgo/internal/runtime.AllocZ"(i64 %1)
-  %3 = alloca %"github.com/goplus/llgo/internal/runtime.Slice", align 8
-  %4 = getelementptr inbounds %"github.com/goplus/llgo/internal/runtime.Slice", ptr %3, i32 0, i32 0
-  store ptr %2, ptr %4, align 8
-  %5 = getelementptr inbounds %"github.com/goplus/llgo/internal/runtime.Slice", ptr %3, i32 0, i32 1
-  store i64 %0, ptr %5, align 4
-  %6 = getelementptr inbounds %"github.com/goplus/llgo/internal/runtime.Slice", ptr %3, i32 0, i32 2
-  store i64 %0, ptr %6, align 4
-  %7 = load %"github.com/goplus/llgo/internal/runtime.Slice", ptr %3, align 8
-  %8 = extractvalue %"github.com/goplus/llgo/internal/runtime.Slice" %7, 1
+  %1 = call %"github.com/goplus/llgo/internal/runtime.Slice" @"github.com/goplus/llgo/internal/runtime.MakeSlice"(i64 %0, i64 %0, i64 8)
+  %2 = extractvalue %"github.com/goplus/llgo/internal/runtime.Slice" %1, 1
   br label %_llgo_1
 
 _llgo_1:                                          ; preds = %_llgo_2, %_llgo_0
-  %9 = phi i64 [ -1, %_llgo_0 ], [ %10, %_llgo_2 ]
-  %10 = add i64 %9, 1
-  %11 = icmp slt i64 %10, %8
-  br i1 %11, label %_llgo_2, label %_llgo_3
+  %3 = phi i64 [ -1, %_llgo_0 ], [ %4, %_llgo_2 ]
+  %4 = add i64 %3, 1
+  %5 = icmp slt i64 %4, %2
+  br i1 %5, label %_llgo_2, label %_llgo_3
 
 _llgo_2:                                          ; preds = %_llgo_1
-  %12 = add i64 %10, 1
-  %13 = extractvalue %"github.com/goplus/llgo/internal/runtime.Slice" %7, 0
-  %14 = extractvalue %"github.com/goplus/llgo/internal/runtime.Slice" %7, 1
-  %15 = icmp slt i64 %10, 0
-  %16 = icmp sge i64 %10, %14
-  %17 = or i1 %16, %15
-  call void @"github.com/goplus/llgo/internal/runtime.AssertIndexRange"(i1 %17)
-  %18 = getelementptr inbounds i64, ptr %13, i64 %10
-  store i64 %12, ptr %18, align 4
+  %6 = add i64 %4, 1
+  %7 = extractvalue %"github.com/goplus/llgo/internal/runtime.Slice" %1, 0
+  %8 = extractvalue %"github.com/goplus/llgo/internal/runtime.Slice" %1, 1
+  %9 = icmp slt i64 %4, 0
+  %10 = icmp sge i64 %4, %8
+  %11 = or i1 %10, %9
+  call void @"github.com/goplus/llgo/internal/runtime.AssertIndexRange"(i1 %11)
+  %12 = getelementptr inbounds i64, ptr %7, i64 %4
+  store i64 %6, ptr %12, align 4
   br label %_llgo_1
 
 _llgo_3:                                          ; preds = %_llgo_1
-  %19 = extractvalue %"github.com/goplus/llgo/internal/runtime.Slice" %7, 1
+  %13 = extractvalue %"github.com/goplus/llgo/internal/runtime.Slice" %1, 1
   br label %_llgo_4
 
 _llgo_4:                                          ; preds = %_llgo_5, %_llgo_3
-  %20 = phi i64 [ 0, %_llgo_3 ], [ %31, %_llgo_5 ]
-  %21 = phi i64 [ -1, %_llgo_3 ], [ %22, %_llgo_5 ]
-  %22 = add i64 %21, 1
-  %23 = icmp slt i64 %22, %19
-  br i1 %23, label %_llgo_5, label %_llgo_6
+  %14 = phi i64 [ 0, %_llgo_3 ], [ %25, %_llgo_5 ]
+  %15 = phi i64 [ -1, %_llgo_3 ], [ %16, %_llgo_5 ]
+  %16 = add i64 %15, 1
+  %17 = icmp slt i64 %16, %13
+  br i1 %17, label %_llgo_5, label %_llgo_6
 
 _llgo_5:                                          ; preds = %_llgo_4
-  %24 = extractvalue %"github.com/goplus/llgo/internal/runtime.Slice" %7, 0
-  %25 = extractvalue %"github.com/goplus/llgo/internal/runtime.Slice" %7, 1
-  %26 = icmp slt i64 %22, 0
-  %27 = icmp sge i64 %22, %25
-  %28 = or i1 %27, %26
-  call void @"github.com/goplus/llgo/internal/runtime.AssertIndexRange"(i1 %28)
-  %29 = getelementptr inbounds i64, ptr %24, i64 %22
-  %30 = load i64, ptr %29, align 4
-  %31 = add i64 %20, %30
+  %18 = extractvalue %"github.com/goplus/llgo/internal/runtime.Slice" %1, 0
+  %19 = extractvalue %"github.com/goplus/llgo/internal/runtime.Slice" %1, 1
+  %20 = icmp slt i64 %16, 0
+  %21 = icmp sge i64 %16, %19
+  %22 = or i1 %21, %20
+  call void @"github.com/goplus/llgo/internal/runtime.AssertIndexRange"(i1 %22)
+  %23 = getelementptr inbounds i64, ptr %18, i64 %16
+  %24 = load i64, ptr %23, align 4
+  %25 = add i64 %14, %24
   br label %_llgo_4
 
 _llgo_6:                                          ; preds = %_llgo_4
-  %32 = sub i64 %0, 1
-  %33 = call i64 @"main.recur1[main.T]"(i64 %32)
-  %34 = add i64 %20, %33
-  ret i64 %34
+  %26 = sub i64 %0, 1
+  %27 = call i64 @"main.recur1[main.T]"(i64 %26)
+  %28 = add i64 %14, %27
+  ret i64 %28
 }
 
-declare ptr @"github.com/goplus/llgo/internal/runtime.AllocZ"(i64)
+declare %"github.com/goplus/llgo/internal/runtime.Slice" @"github.com/goplus/llgo/internal/runtime.MakeSlice"(i64, i64, i64)
 
 declare void @"github.com/goplus/llgo/internal/runtime.AssertIndexRange"(i1)
diff --git a/cl/_testrt/intgen/out.ll b/cl/_testrt/intgen/out.ll
index 5908ac5b..1ffc9428 100644
--- a/cl/_testrt/intgen/out.ll
+++ b/cl/_testrt/intgen/out.ll
@@ -13,41 +13,32 @@ source_filename = "main"
 
 define %"github.com/goplus/llgo/internal/runtime.Slice" @main.genInts(i64 %0, { ptr, ptr } %1) {
 _llgo_0:
-  %2 = mul i64 %0, 4
-  %3 = call ptr @"github.com/goplus/llgo/internal/runtime.AllocZ"(i64 %2)
-  %4 = alloca %"github.com/goplus/llgo/internal/runtime.Slice", align 8
-  %5 = getelementptr inbounds %"github.com/goplus/llgo/internal/runtime.Slice", ptr %4, i32 0, i32 0
-  store ptr %3, ptr %5, align 8
-  %6 = getelementptr inbounds %"github.com/goplus/llgo/internal/runtime.Slice", ptr %4, i32 0, i32 1
-  store i64 %0, ptr %6, align 4
-  %7 = getelementptr inbounds %"github.com/goplus/llgo/internal/runtime.Slice", ptr %4, i32 0, i32 2
-  store i64 %0, ptr %7, align 4
-  %8 = load %"github.com/goplus/llgo/internal/runtime.Slice", ptr %4, align 8
-  %9 = extractvalue %"github.com/goplus/llgo/internal/runtime.Slice" %8, 1
+  %2 = call %"github.com/goplus/llgo/internal/runtime.Slice" @"github.com/goplus/llgo/internal/runtime.MakeSlice"(i64 %0, i64 %0, i64 4)
+  %3 = extractvalue %"github.com/goplus/llgo/internal/runtime.Slice" %2, 1
   br label %_llgo_1
 
 _llgo_1:                                          ; preds = %_llgo_2, %_llgo_0
-  %10 = phi i64 [ -1, %_llgo_0 ], [ %11, %_llgo_2 ]
-  %11 = add i64 %10, 1
-  %12 = icmp slt i64 %11, %9
-  br i1 %12, label %_llgo_2, label %_llgo_3
+  %4 = phi i64 [ -1, %_llgo_0 ], [ %5, %_llgo_2 ]
+  %5 = add i64 %4, 1
+  %6 = icmp slt i64 %5, %3
+  br i1 %6, label %_llgo_2, label %_llgo_3
 
 _llgo_2:                                          ; preds = %_llgo_1
-  %13 = extractvalue { ptr, ptr } %1, 1
-  %14 = extractvalue { ptr, ptr } %1, 0
-  %15 = call i32 %14(ptr %13)
-  %16 = extractvalue %"github.com/goplus/llgo/internal/runtime.Slice" %8, 0
-  %17 = extractvalue %"github.com/goplus/llgo/internal/runtime.Slice" %8, 1
-  %18 = icmp slt i64 %11, 0
-  %19 = icmp sge i64 %11, %17
-  %20 = or i1 %19, %18
-  call void @"github.com/goplus/llgo/internal/runtime.AssertIndexRange"(i1 %20)
-  %21 = getelementptr inbounds i32, ptr %16, i64 %11
-  store i32 %15, ptr %21, align 4
+  %7 = extractvalue { ptr, ptr } %1, 1
+  %8 = extractvalue { ptr, ptr } %1, 0
+  %9 = call i32 %8(ptr %7)
+  %10 = extractvalue %"github.com/goplus/llgo/internal/runtime.Slice" %2, 0
+  %11 = extractvalue %"github.com/goplus/llgo/internal/runtime.Slice" %2, 1
+  %12 = icmp slt i64 %5, 0
+  %13 = icmp sge i64 %5, %11
+  %14 = or i1 %13, %12
+  call void @"github.com/goplus/llgo/internal/runtime.AssertIndexRange"(i1 %14)
+  %15 = getelementptr inbounds i32, ptr %10, i64 %5
+  store i32 %9, ptr %15, align 4
   br label %_llgo_1
 
 _llgo_3:                                          ; preds = %_llgo_1
-  ret %"github.com/goplus/llgo/internal/runtime.Slice" %8
+  ret %"github.com/goplus/llgo/internal/runtime.Slice" %2
 }
 
 define i32 @"main.(*generator).next"(ptr %0) {
@@ -195,7 +186,7 @@ _llgo_0:
   ret i32 %7
 }
 
-declare ptr @"github.com/goplus/llgo/internal/runtime.AllocZ"(i64)
+declare %"github.com/goplus/llgo/internal/runtime.Slice" @"github.com/goplus/llgo/internal/runtime.MakeSlice"(i64, i64, i64)
 
 declare void @"github.com/goplus/llgo/internal/runtime.AssertIndexRange"(i1)
 
@@ -211,6 +202,8 @@ _llgo_0:
 
 declare i32 @printf(ptr, ...)
 
+declare ptr @"github.com/goplus/llgo/internal/runtime.AllocZ"(i64)
+
 declare ptr @"github.com/goplus/llgo/internal/runtime.AllocU"(i64)
 
 define i32 @"main.next$bound"(ptr %0) {
diff --git a/cl/compile.go b/cl/compile.go
index 4517303e..419618cf 100644
--- a/cl/compile.go
+++ b/cl/compile.go
@@ -543,12 +543,9 @@ func (p *context) compileInstrOrValue(b llssa.Builder, iv instrOrValue, asValue
 		x := p.compileValue(b, v.X)
 		ret = b.MakeInterface(t, x)
 	case *ssa.MakeSlice:
-		var nCap llssa.Expr
 		t := p.prog.Type(v.Type(), llssa.InGo)
 		nLen := p.compileValue(b, v.Len)
-		if v.Cap != nil {
-			nCap = p.compileValue(b, v.Cap)
-		}
+		nCap := p.compileValue(b, v.Cap)
 		ret = b.MakeSlice(t, nLen, nCap)
 	case *ssa.MakeMap:
 		var nReserve llssa.Expr
diff --git a/internal/runtime/goarch/goarch.go b/internal/runtime/goarch/goarch.go
new file mode 100644
index 00000000..24c0de95
--- /dev/null
+++ b/internal/runtime/goarch/goarch.go
@@ -0,0 +1,3 @@
+package goarch
+
+const PtrSize = 4 << (^uintptr(0) >> 63)
diff --git a/internal/runtime/math/math.go b/internal/runtime/math/math.go
new file mode 100644
index 00000000..8d38eab8
--- /dev/null
+++ b/internal/runtime/math/math.go
@@ -0,0 +1,15 @@
+package math
+
+import "github.com/goplus/llgo/internal/runtime/goarch"
+
+const MaxUintptr = ^uintptr(0)
+
+// MulUintptr returns a * b and whether the multiplication overflowed.
+// On supported platforms this is an intrinsic lowered by the compiler.
+func MulUintptr(a, b uintptr) (uintptr, bool) {
+	if a|b < 1<<(4*goarch.PtrSize) || a == 0 {
+		return a * b, false
+	}
+	overflow := b > MaxUintptr/a
+	return a * b, overflow
+}
diff --git a/internal/runtime/stubs.go b/internal/runtime/stubs.go
index ed8b9a8d..0b81dc67 100644
--- a/internal/runtime/stubs.go
+++ b/internal/runtime/stubs.go
@@ -36,3 +36,10 @@ func fastrand() uint32 {
 	return s0 + s1
 }
 */
+
+const (
+	// _64bit = 1 on 64-bit systems, 0 on 32-bit systems
+	_64bit       = 1 << (^uintptr(0) >> 63) / 2
+	heapAddrBits = (_64bit)*48 + (1-_64bit)*(32)
+	maxAlloc     = (1 << heapAddrBits) - (1-_64bit)*1
+)
diff --git a/internal/runtime/z_slice.go b/internal/runtime/z_slice.go
index 3c31710f..6eed5167 100644
--- a/internal/runtime/z_slice.go
+++ b/internal/runtime/z_slice.go
@@ -20,6 +20,7 @@ import (
 	"unsafe"
 
 	"github.com/goplus/llgo/c"
+	"github.com/goplus/llgo/internal/runtime/math"
 )
 
 // -----------------------------------------------------------------------------
@@ -120,4 +121,24 @@ func SliceCopy(dst Slice, data unsafe.Pointer, num int, etSize int) int {
 	return n
 }
 
+func MakeSlice(len, cap int, etSize int) Slice {
+	mem, overflow := math.MulUintptr(uintptr(etSize), uintptr(cap))
+	if overflow || mem > maxAlloc || len < 0 || len > cap {
+		mem, overflow := math.MulUintptr(uintptr(etSize), uintptr(len))
+		if overflow || mem > maxAlloc || len < 0 {
+			panicmakeslicelen()
+		}
+		panicmakeslicecap()
+	}
+	return Slice{AllocZ(mem), len, cap}
+}
+
+func panicmakeslicelen() {
+	panic(errorString("makeslice: len out of range"))
+}
+
+func panicmakeslicecap() {
+	panic(errorString("makeslice: cap out of range"))
+}
+
 // -----------------------------------------------------------------------------
diff --git a/ssa/datastruct.go b/ssa/datastruct.go
index 2f45c7b6..9ce447fa 100644
--- a/ssa/datastruct.go
+++ b/ssa/datastruct.go
@@ -416,16 +416,25 @@ func (b Builder) MakeSlice(t Type, len, cap Expr) (ret Expr) {
 		log.Printf("MakeSlice %v, %v, %v\n", t.RawType(), len.impl, cap.impl)
 	}
 	prog := b.Prog
-	if cap.IsNil() {
-		cap = len
-	}
+	len = b.fitIntSize(len)
+	cap = b.fitIntSize(cap)
 	telem := prog.Index(t)
-	ptr := b.ArrayAlloc(telem, cap)
-	ret.impl = b.unsafeSlice(ptr, len.impl, cap.impl).impl
+	ret = b.InlineCall(b.Pkg.rtFunc("MakeSlice"), len, cap, prog.IntVal(prog.SizeOf(telem), prog.Int()))
 	ret.Type = t
 	return
 }
 
+// fit size to int
+func (b Builder) fitIntSize(n Expr) Expr {
+	prog := b.Prog
+	typ := prog.Int()
+	if prog.SizeOf(n.Type) != prog.SizeOf(typ) {
+		n.Type = typ
+		n.impl = castInt(b, n.impl, typ)
+	}
+	return n
+}
+
 // -----------------------------------------------------------------------------
 
 // The MakeMap instruction creates a new hash-table-based map object