diff --git a/crates/cli-support/src/descriptor.rs b/crates/cli-support/src/descriptor.rs
index bd6bc25f7..b98a2ec5e 100644
--- a/crates/cli-support/src/descriptor.rs
+++ b/crates/cli-support/src/descriptor.rs
@@ -187,6 +187,12 @@ impl Descriptor {
                     _ => return None,
                 }
             }
+            Descriptor::RefMut(ref d) => {
+                match **d {
+                    Descriptor::Slice(ref d) => &**d,
+                    _ => return None,
+                }
+            }
             _ => return None,
         };
         match *inner {
@@ -234,6 +240,13 @@ impl Descriptor {
             _ => false,
         }
     }
+
+    pub fn is_mut_ref(&self) -> bool {
+        match *self {
+            Descriptor::RefMut(_) => true,
+            _ => false,
+        }
+    }
 }
 
 fn get(a: &mut &[u32]) -> u32 {
diff --git a/crates/cli-support/src/js/js2rust.rs b/crates/cli-support/src/js/js2rust.rs
index d4f9d7391..d300e79e3 100644
--- a/crates/cli-support/src/js/js2rust.rs
+++ b/crates/cli-support/src/js/js2rust.rs
@@ -118,6 +118,15 @@ impl<'a, 'b> Js2Rust<'a, 'b> {
                 setGlobalArgument(len{i}, {global_idx});\n\
             ", i = i, func = func, arg = name, global_idx = global_idx));
             if arg.is_by_ref() {
+                if arg.is_mut_ref() {
+                    let get = self.cx.memview_function(kind);
+                    self.finally(&format!("\
+                        {arg}.set({get}().subarray(\
+                            ptr{i} / {size}, \
+                            ptr{i} / {size} + len{i}\
+                        ));\n\
+                    ", i = i, arg = name, get = get, size = kind.size()));
+                }
                 self.finally(&format!("\
                     wasm.__wbindgen_free(ptr{i}, len{i} * {size});\n\
                 ", i = i, size = kind.size()));
diff --git a/crates/cli-support/src/js/mod.rs b/crates/cli-support/src/js/mod.rs
index b6dba1c6b..f9c84db68 100644
--- a/crates/cli-support/src/js/mod.rs
+++ b/crates/cli-support/src/js/mod.rs
@@ -926,7 +926,7 @@ impl<'a> Context<'a> {
         self.expose_uint8_memory();
         self.global(&format!("
             function getStringFromWasm(ptr, len) {{
-                return cachedDecoder.decode(getUint8Memory().slice(ptr, ptr + len));
+                return cachedDecoder.decode(getUint8Memory().subarray(ptr, ptr + len));
             }}
         "));
     }
@@ -940,7 +940,7 @@ impl<'a> Context<'a> {
         self.global(&format!("
             function getArrayJsValueFromWasm(ptr, len) {{
                 const mem = getUint32Memory();
-                const slice = mem.slice(ptr / 4, ptr / 4 + len);
+                const slice = mem.subarray(ptr / 4, ptr / 4 + len);
                 const result = [];
                 for (let i = 0; i < slice.length; i++) {{
                     result.push(takeObject(slice[i]))
@@ -951,158 +951,154 @@ impl<'a> Context<'a> {
     }
 
     fn expose_get_array_i8_from_wasm(&mut self) {
-        self.expose_uint8_memory();
-        if !self.exposed_globals.insert("get_array_i8_from_wasm") {
-            return;
-        }
-        self.global(&format!("
-            function getArrayI8FromWasm(ptr, len) {{
-                const mem = getUint8Memory();
-                const slice = mem.slice(ptr, ptr + len);
-                return new Int8Array(slice);
-            }}
-        "));
+        self.expose_int8_memory();
+        self.arrayget("getArrayI8FromWasm", "getInt8Memory", 1);
     }
 
     fn expose_get_array_u8_from_wasm(&mut self) {
         self.expose_uint8_memory();
-        if !self.exposed_globals.insert("get_array_u8_from_wasm") {
-            return;
-        }
-        self.global(&format!("
-            function getArrayU8FromWasm(ptr, len) {{
-                const mem = getUint8Memory();
-                const slice = mem.slice(ptr, ptr + len);
-                return new Uint8Array(slice);
-            }}
-        "));
+        self.arrayget("getArrayU8FromWasm", "getUint8Memory", 1);
     }
 
     fn expose_get_array_i16_from_wasm(&mut self) {
-        self.expose_uint16_memory();
-        if !self.exposed_globals.insert("get_array_i16_from_wasm") {
-            return;
-        }
-        self.global(&format!("
-            function getArrayI16FromWasm(ptr, len) {{
-                const mem = getUint16Memory();
-                const slice = mem.slice(ptr / 2, ptr / 2 + len);
-                return new Int16Array(slice);
-            }}
-        "));
+        self.expose_int16_memory();
+        self.arrayget("getArrayI16FromWasm", "getInt16Memory", 2);
     }
 
     fn expose_get_array_u16_from_wasm(&mut self) {
         self.expose_uint16_memory();
-        if !self.exposed_globals.insert("get_array_u16_from_wasm") {
-            return;
-        }
-        self.global(&format!("
-            function getArrayU16FromWasm(ptr, len) {{
-                const mem = getUint16Memory();
-                const slice = mem.slice(ptr / 2, ptr / 2 + len);
-                return new Uint16Array(slice);
-            }}
-        "));
+        self.arrayget("getArrayU16FromWasm", "getUint16Memory", 2);
     }
 
     fn expose_get_array_i32_from_wasm(&mut self) {
-        self.expose_uint32_memory();
-        if !self.exposed_globals.insert("get_array_i32_from_wasm") {
-            return;
-        }
-        self.global(&format!("
-            function getArrayI32FromWasm(ptr, len) {{
-                const mem = getUint32Memory();
-                const slice = mem.slice(ptr / 4, ptr / 4 + len);
-                return new Int32Array(slice);
-            }}
-        "));
+        self.expose_int32_memory();
+        self.arrayget("getArrayI32FromWasm", "getInt32Memory", 4);
     }
 
     fn expose_get_array_u32_from_wasm(&mut self) {
         self.expose_uint32_memory();
-        if !self.exposed_globals.insert("get_array_u32_from_wasm") {
-            return;
-        }
-        self.global(&format!("
-            function getArrayU32FromWasm(ptr, len) {{
-                const mem = getUint32Memory();
-                const slice = mem.slice(ptr / 4, ptr / 4 + len);
-                return new Uint32Array(slice);
-            }}
-        "));
+        self.arrayget("getArrayU32FromWasm", "getUint32Memory", 4);
     }
 
     fn expose_get_array_f32_from_wasm(&mut self) {
-        if !self.exposed_globals.insert("get_array_f32_from_wasm") {
-            return;
-        }
-        self.global(&format!("
-            function getArrayF32FromWasm(ptr, len) {{
-                const mem = new Float32Array(wasm.memory.buffer);
-                const slice = mem.slice(ptr / 4,  ptr / 4 + len);
-                return new Float32Array(slice);
-            }}
-        "));
+        self.expose_f32_memory();
+        self.arrayget("getArrayF32FromWasm", "getFloat32Memory", 4);
     }
 
     fn expose_get_array_f64_from_wasm(&mut self) {
-        if !self.exposed_globals.insert("get_array_f64_from_wasm") {
+        self.expose_f64_memory();
+        self.arrayget("getArrayF64FromWasm", "getFloat64Memory", 8);
+    }
+
+    fn arrayget(&mut self, name: &'static str, mem: &'static str, size: usize) {
+        if !self.exposed_globals.insert(name) {
             return;
         }
         self.global(&format!("
-            function getArrayF64FromWasm(ptr, len) {{
-                const mem = new Float64Array(wasm.memory.buffer);
-                const slice = mem.slice(ptr / 8,  ptr / 8 + len);
-                return new Float64Array(slice);
+            function {name}(ptr, len) {{
+                return {mem}().subarray(ptr / {size}, ptr / {size} + len);
             }}
-        "));
+        ",
+            name = name,
+            mem = mem,
+            size = size,
+        ));
+    }
+
+    fn expose_int8_memory(&mut self) {
+        self.memview("getInt8Memory", "Int8Array");
     }
 
     fn expose_uint8_memory(&mut self) {
-        if !self.exposed_globals.insert("uint8_memory") {
-            return;
-        }
-        self.global(&format!("
-            let cachedUint8Memory = null;
-            function getUint8Memory() {{
-                if (cachedUint8Memory === null ||
-                    cachedUint8Memory.buffer !== wasm.memory.buffer)
-                    cachedUint8Memory = new Uint8Array(wasm.memory.buffer);
-                return cachedUint8Memory;
-            }}
-        "));
+        self.memview("getUint8Memory", "Uint8Array");
+    }
+
+    fn expose_int16_memory(&mut self) {
+        self.memview("getInt16Memory", "Int16Array");
     }
 
     fn expose_uint16_memory(&mut self) {
-        if !self.exposed_globals.insert("uint16_memory") {
-            return;
-        }
-        self.global(&format!("
-            let cachedUint16Memory = null;
-            function getUint16Memory() {{
-                if (cachedUint16Memory === null ||
-                    cachedUint16Memory.buffer !== wasm.memory.buffer)
-                    cachedUint16Memory = new Uint16Array(wasm.memory.buffer);
-                return cachedUint16Memory;
-            }}
-        "));
+        self.memview("getUint16Memory", "Uint16Array");
+    }
+
+    fn expose_int32_memory(&mut self) {
+        self.memview("getInt32Memory", "Int32Array");
     }
 
     fn expose_uint32_memory(&mut self) {
-        if !self.exposed_globals.insert("uint32_memory") {
+        self.memview("getUint32Memory", "Uint32Array");
+    }
+
+    fn expose_f32_memory(&mut self) {
+        self.memview("getFloat32Memory", "Float32Array");
+    }
+
+    fn expose_f64_memory(&mut self) {
+        self.memview("getFloat64Memory", "Float64Array");
+    }
+
+    fn memview_function(&mut self, t: VectorKind) -> &'static str {
+        match t {
+            VectorKind::String => {
+                self.expose_uint8_memory();
+                "getUint8Memory"
+            }
+            VectorKind::I8 => {
+                self.expose_int8_memory();
+                "getInt8Memory"
+            }
+            VectorKind::U8 => {
+                self.expose_uint8_memory();
+                "getUint8Memory"
+            }
+            VectorKind::I16 => {
+                self.expose_int16_memory();
+                "getInt16Memory"
+            }
+            VectorKind::U16 => {
+                self.expose_uint16_memory();
+                "getUint16Memory"
+            }
+            VectorKind::I32 => {
+                self.expose_int32_memory();
+                "getInt32Memory"
+            }
+            VectorKind::U32 => {
+                self.expose_uint32_memory();
+                "getUint32Memory"
+            }
+            VectorKind::F32 => {
+                self.expose_f32_memory();
+                "getFloat32Memory"
+            }
+            VectorKind::F64 => {
+                self.expose_f64_memory();
+                "getFloat64Memory"
+            }
+            VectorKind::Anyref => {
+                self.expose_uint32_memory();
+                "getUint32Memory"
+            }
+        }
+    }
+
+
+    fn memview(&mut self, name: &'static str, js: &str) {
+        if !self.exposed_globals.insert(name) {
             return;
         }
         self.global(&format!("
-            let cachedUint32Memory = null;
-            function getUint32Memory() {{
-                if (cachedUint32Memory === null ||
-                    cachedUint32Memory.buffer !== wasm.memory.buffer)
-                    cachedUint32Memory = new Uint32Array(wasm.memory.buffer);
-                return cachedUint32Memory;
+            let cache{name} = null;
+            function {name}() {{
+                if (cache{name} === null ||
+                    cache{name}.buffer !== wasm.memory.buffer)
+                    cache{name} = new {js}(wasm.memory.buffer);
+                return cache{name};
             }}
-        "));
+        ",
+            name = name,
+            js = js,
+        ));
     }
 
     fn expose_assert_class(&mut self) {
@@ -1268,6 +1264,60 @@ impl<'a> Context<'a> {
         }
     }
 
+    fn expose_commit_slice_to_wasm(&mut self, ty: VectorKind)
+        -> Result<&'static str, Error>
+    {
+        let gen = |me: &mut Context, name: &'static str, size: usize, get: &str| {
+            me.global(&format!("
+                function {name}(ptr, view) {{
+                    if (view.buffer !== wasm.memory.buffer)
+                        {get}().set(view, ptr / {size});
+                }}
+            ",
+                name = name,
+                size = size,
+                get = get,
+            ));
+            name
+        };
+        match ty {
+            VectorKind::String => bail!("strings cannot be used with mutable slices"),
+            VectorKind::Anyref => bail!("js values cannot be used with mutable slices"),
+            VectorKind::I8 => {
+                self.expose_int8_memory();
+                Ok(gen(self, "commitI8ToWasm", 1, "getInt8Memory"))
+            }
+            VectorKind::U8 => {
+                self.expose_uint8_memory();
+                Ok(gen(self, "commitU8ToWasm", 1, "getUint8Memory"))
+            }
+            VectorKind::I16 => {
+                self.expose_int16_memory();
+                Ok(gen(self, "commitI16ToWasm", 2, "getInt16Memory"))
+            }
+            VectorKind::U16 => {
+                self.expose_uint16_memory();
+                Ok(gen(self, "commitU16ToWasm", 2, "getUint16Memory"))
+            }
+            VectorKind::I32 => {
+                self.expose_int32_memory();
+                Ok(gen(self, "commitI32ToWasm", 4, "getInt32Memory"))
+            }
+            VectorKind::U32 => {
+                self.expose_uint32_memory();
+                Ok(gen(self, "commitU32ToWasm", 4, "getUint32Memory"))
+            }
+            VectorKind::F32 => {
+                self.expose_f32_memory();
+                Ok(gen(self, "commitF32ToWasm", 4, "getFloat32Memory"))
+            }
+            VectorKind::F64 => {
+                self.expose_f64_memory();
+                Ok(gen(self, "commitF64ToWasm", 8, "getFloat64Memory"))
+            }
+        }
+    }
+
     fn expose_set_global_argument(&mut self) -> Result<(), Error> {
         if !self.exposed_globals.insert("set_global_argument") {
             return Ok(());
diff --git a/crates/cli-support/src/js/rust2js.rs b/crates/cli-support/src/js/rust2js.rs
index bd46778de..d47369e48 100644
--- a/crates/cli-support/src/js/rust2js.rs
+++ b/crates/cli-support/src/js/rust2js.rs
@@ -92,6 +92,9 @@ impl<'a, 'b> Rust2Js<'a, 'b> {
                     wasm.__wbindgen_free(arg{0}, len{0} * {size});\
                 ", i, size = ty.size()));
                 self.cx.require_internal_export("__wbindgen_free")?;
+            } else if arg.is_mut_ref() {
+                let f = self.cx.expose_commit_slice_to_wasm(ty)?;
+                self.finally(&format!("{}(arg{i}, v{i});", f, i = i));
             }
             self.js_arguments.push(format!("v{}", i));
             return Ok(())
diff --git a/src/convert.rs b/src/convert.rs
index 80d49f249..82fb908af 100644
--- a/src/convert.rs
+++ b/src/convert.rs
@@ -170,6 +170,14 @@ macro_rules! vectors {
             }
         }
 
+        impl<'a> IntoWasmAbi for &'a mut [$t] {
+            type Abi = u32;
+
+            fn into_abi(self, extra: &mut Stack) -> u32 {
+                (&*self).into_abi(extra)
+            }
+        }
+
         impl RefFromWasmAbi for [$t] {
             type Abi = u32;
             type Anchor = &'static [$t];
@@ -181,6 +189,18 @@ macro_rules! vectors {
                 )
             }
         }
+
+        impl RefMutFromWasmAbi for [$t] {
+            type Abi = u32;
+            type Anchor = &'static mut [$t];
+
+            unsafe fn ref_mut_from_abi(js: u32, extra: &mut Stack) -> &'static mut [$t] {
+                slice::from_raw_parts_mut(
+                    <*mut $t>::from_abi(js, extra),
+                    extra.pop() as usize,
+                )
+            }
+        }
     )*)
 }
 
diff --git a/tests/all/slice.rs b/tests/all/slice.rs
index f3bfab675..13a59bb25 100644
--- a/tests/all/slice.rs
+++ b/tests/all/slice.rs
@@ -278,3 +278,225 @@ fn pass_array_works() {
         "#)
         .test();
 }
+
+#[test]
+fn import_mut() {
+    project()
+        .file("src/lib.rs", r#"
+            #![feature(proc_macro, wasm_custom_section, wasm_import_module)]
+
+            extern crate wasm_bindgen;
+
+            use wasm_bindgen::prelude::*;
+
+            macro_rules! doit {
+                ($(($rust:ident, $js:ident, $i:ident))*) => (
+                    $(
+                        #[wasm_bindgen(module = "./test")]
+                        extern {
+                            fn $js(a: &mut [$i]);
+                        }
+
+                        fn $rust() {
+                            let mut buf = [
+                                1 as $i,
+                                2 as $i,
+                                3 as $i,
+                            ];
+                            $js(&mut buf);
+                            assert_eq!(buf[0], 4 as $i);
+                            assert_eq!(buf[1], 5 as $i);
+                            assert_eq!(buf[2], 3 as $i);
+                        }
+                    )*
+
+                    #[wasm_bindgen]
+                    pub fn run() {
+                        $($rust();)*
+                    }
+                )
+            }
+
+
+            doit! {
+                (rust_i8, js_i8, i8)
+                (rust_u8, js_u8, u8)
+                (rust_i16, js_i16, i16)
+                (rust_u16, js_u16, u16)
+                (rust_i32, js_i32, i32)
+                (rust_u32, js_u32, u32)
+                (rust_f32, js_f32, f32)
+                (rust_f64, js_f64, f64)
+            }
+        "#)
+        .file("test.ts", r#"
+            import * as assert from "assert";
+            import * as wasm from "./out";
+
+            function foo(a: any) {
+                assert.strictEqual(a.length, 3);
+                assert.strictEqual(a[0], 1);
+                assert.strictEqual(a[1], 2);
+                a[0] = 4;
+                a[1] = 5;
+            }
+
+            export const js_i8 = foo;
+            export const js_u8 = foo;
+            export const js_i16 = foo;
+            export const js_u16 = foo;
+            export const js_i32 = foo;
+            export const js_u32 = foo;
+            export const js_f32 = foo;
+            export const js_f64 = foo;
+
+            export function test() {
+                wasm.run();
+            }
+        "#)
+        .test();
+}
+
+#[test]
+fn import_mut_realloc_middle() {
+    project()
+        .file("src/lib.rs", r#"
+            #![feature(proc_macro, wasm_custom_section, wasm_import_module)]
+
+            extern crate wasm_bindgen;
+
+            use wasm_bindgen::prelude::*;
+
+            macro_rules! doit {
+                ($(($rust:ident, $js:ident, $i:ident))*) => (
+                    $(
+                        #[wasm_bindgen(module = "./test")]
+                        extern {
+                            fn $js(a: &mut [$i]);
+                        }
+
+                        fn $rust() {
+                            let mut buf = [
+                                1 as $i,
+                                2 as $i,
+                                3 as $i,
+                            ];
+                            $js(&mut buf);
+                            assert_eq!(buf[0], 4 as $i);
+                            assert_eq!(buf[1], 5 as $i);
+                            assert_eq!(buf[2], 3 as $i);
+                        }
+                    )*
+
+                    #[wasm_bindgen]
+                    pub fn run() {
+                        $($rust();)*
+                    }
+
+                    #[wasm_bindgen]
+                    pub fn allocate() {
+                        std::mem::forget(Vec::<u8>::with_capacity(128 * 1024));
+                    }
+                )
+            }
+
+
+            doit! {
+                (rust_i8, js_i8, i8)
+                (rust_u8, js_u8, u8)
+                (rust_i16, js_i16, i16)
+                (rust_u16, js_u16, u16)
+                (rust_i32, js_i32, i32)
+                (rust_u32, js_u32, u32)
+                (rust_f32, js_f32, f32)
+                (rust_f64, js_f64, f64)
+            }
+        "#)
+        .file("test.ts", r#"
+            import * as assert from "assert";
+            import * as wasm from "./out";
+
+            function foo(a: any) {
+                wasm.allocate();
+                assert.strictEqual(a.length, 3);
+                assert.strictEqual(a[0], 1);
+                assert.strictEqual(a[1], 2);
+                a[0] = 4;
+                a[1] = 5;
+            }
+
+            export const js_i8 = foo;
+            export const js_u8 = foo;
+            export const js_i16 = foo;
+            export const js_u16 = foo;
+            export const js_i32 = foo;
+            export const js_u32 = foo;
+            export const js_f32 = foo;
+            export const js_f64 = foo;
+
+            export function test() {
+                wasm.run();
+            }
+        "#)
+        .test();
+}
+
+#[test]
+fn export_mut() {
+    project()
+        .file("src/lib.rs", r#"
+            #![feature(proc_macro, wasm_custom_section)]
+
+            extern crate wasm_bindgen;
+
+            use wasm_bindgen::prelude::*;
+
+            macro_rules! doit {
+                ($($i:ident)*) => ($(
+                    #[wasm_bindgen]
+                    pub fn $i(a: &mut [$i])  {
+                        assert_eq!(a.len(), 3);
+                        assert_eq!(a[0], 1 as $i);
+                        assert_eq!(a[1], 2 as $i);
+                        assert_eq!(a[2], 3 as $i);
+                        a[0] = 4 as $i;
+                        a[1] = 5 as $i;
+                    }
+                )*)
+            }
+
+
+            doit! { i8 u8 i16 u16 i32 u32 f32 f64 }
+        "#)
+        .file("test.ts", r#"
+            import * as assert from "assert";
+            import * as wasm from "./out";
+
+            function run(a: any, rust: any) {
+                assert.strictEqual(a.length, 3);
+                a[0] = 1;
+                a[1] = 2;
+                a[2] = 3;
+                console.log(a);
+                rust(a);
+                console.log(a);
+                assert.strictEqual(a.length, 3);
+                assert.strictEqual(a[0], 4);
+                assert.strictEqual(a[1], 5);
+                assert.strictEqual(a[2], 3);
+            }
+
+            export function test() {
+                run(new Int8Array(3), wasm.i8);
+                run(new Uint8Array(3), wasm.u8);
+                run(new Int16Array(3), wasm.i16);
+                run(new Uint16Array(3), wasm.u16);
+                run(new Int32Array(3), wasm.i32);
+                run(new Uint32Array(3), wasm.u32);
+                run(new Float32Array(3), wasm.f32);
+                run(new Float64Array(3), wasm.f64);
+          }
+      "#)
+        .test();
+}
+