diff --git a/examples/lock2.rs b/examples/lock2.rs
new file mode 100644
index 0000000000..ab41cf8a74
--- /dev/null
+++ b/examples/lock2.rs
@@ -0,0 +1,40 @@
+//! examples/lock2.rs
+
+#![deny(unsafe_code)]
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+use cortex_m_semihosting::debug;
+use lm3s6965::Interrupt;
+
+#[rtic::app(device = lm3s6965)]
+const APP: () = {
+    struct Resources {
+        #[init(0)]
+        shared: u32,
+        #[init(0)]
+        shared2: u32,
+    }
+
+    #[init]
+    fn init(_: init::Context) {
+        rtic::pend(Interrupt::GPIOA);
+    }
+
+    // when omitted priority is assumed to be `1`
+    #[task(binds = GPIOA, resources = [shared, shared2])]
+    fn gpioa(mut c: gpioa::Context) {
+        c.resources.shared.lock(|shared| {
+            *shared += 1;
+            rtic::pend(Interrupt::GPIOB);
+        });
+
+        debug::exit(debug::EXIT_SUCCESS);
+    }
+
+    #[task(binds = GPIOB, priority = 2, resources = [shared, shared2])]
+    fn gpiob(c: gpiob::Context) {
+        *c.resources.shared += 1;
+    }
+};
diff --git a/expand_lock.rs b/expand_lock.rs
new file mode 100644
index 0000000000..2490cbe79b
--- /dev/null
+++ b/expand_lock.rs
@@ -0,0 +1,114 @@
+#![feature(prelude_import)]
+//! examples/lock2.rs
+#![deny(unsafe_code)]
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+#[prelude_import]
+use core::prelude::v1::*;
+#[macro_use]
+extern crate core;
+#[macro_use]
+extern crate compiler_builtins;
+use cortex_m_semihosting::debug;
+use lm3s6965::Interrupt;
+#[allow(non_snake_case)]
+fn init(_: init::Context) {
+    rtic::pend(Interrupt::GPIOA);
+}
+#[allow(non_snake_case)]
+fn gpioa(mut c: gpioa::Context) {
+    use rtic::Mutex as _;
+    c.resources.shared.lock(|shared| {
+        *shared += 1;
+        rtic::pend(Interrupt::GPIOB);
+    });
+    debug::exit(debug::EXIT_SUCCESS);
+}
+#[allow(non_snake_case)]
+fn gpiob(c: gpiob::Context) {
+    use rtic::Mutex as _;
+    *c.resources.shared += 1;
+}
+#[allow(non_snake_case)]
+///Initialization function
+pub mod init {
+    /// Execution context
+    pub struct Context {
+        /// Core (Cortex-M) peripherals
+        pub core: rtic::export::Peripherals,
+    }
+    impl Context {
+        #[inline(always)]
+        pub unsafe fn new(core: rtic::export::Peripherals) -> Self {
+            Context { core }
+        }
+    }
+}
+mod resources {
+    use rtic::export::Priority;
+    #[allow(non_camel_case_types)]
+    pub struct shared<'a> {
+        priority: &'a Priority,
+    }
+    impl<'a> shared<'a> {
+        #[inline(always)]
+        pub unsafe fn new(priority: &'a Priority) -> Self {
+            shared { priority }
+        }
+        #[inline(always)]
+        pub unsafe fn priority(&self) -> &Priority {
+            self.priority
+        }
+    }
+}
+#[allow(non_snake_case)]
+///Resources `gpioa` has access to
+pub struct gpioaResources<'a> {
+    pub shared: resources::shared<'a>,
+}
+#[allow(non_snake_case)]
+///Hardware task
+pub mod gpioa {
+    #[doc(inline)]
+    pub use super::gpioaResources as Resources;
+    /// Execution context
+    pub struct Context<'a> {
+        /// Resources this task has access to
+        pub resources: Resources<'a>,
+    }
+    impl<'a> Context<'a> {
+        #[inline(always)]
+        pub unsafe fn new(priority: &'a rtic::export::Priority) -> Self {
+            Context {
+                resources: Resources::new(priority),
+            }
+        }
+    }
+}
+#[allow(non_snake_case)]
+///Resources `gpiob` has access to
+pub struct gpiobResources<'a> {
+    pub shared: &'a mut u32,
+}
+#[allow(non_snake_case)]
+///Hardware task
+pub mod gpiob {
+    #[doc(inline)]
+    pub use super::gpiobResources as Resources;
+    /// Execution context
+    pub struct Context<'a> {
+        /// Resources this task has access to
+        pub resources: Resources<'a>,
+    }
+    impl<'a> Context<'a> {
+        #[inline(always)]
+        pub unsafe fn new(priority: &'a rtic::export::Priority) -> Self {
+            Context {
+                resources: Resources::new(priority),
+            }
+        }
+    }
+}
+/// Implementation details
+const APP: () = { # [ doc = r" Always include the device crate which contains the vector table" ] use lm3s6965 as _ ; # [ allow ( non_upper_case_globals ) ] static mut shared : u32 = 0 ; impl < 'a > rtic :: Mutex for resources :: shared < 'a > { type T = u32 ; # [ inline ( always ) ] fn lock < R > ( & mut self , f : impl FnOnce ( & mut u32 ) -> R ) -> R { # [ doc = r" Priority ceiling" ] const CEILING : u8 = 2u8 ; unsafe { rtic :: export :: lock ( & mut shared , self . priority ( ) , CEILING , lm3s6965 :: NVIC_PRIO_BITS , f ) } } } # [ allow ( non_snake_case ) ] # [ no_mangle ] unsafe fn GPIOA ( ) { const PRIORITY : u8 = 1u8 ; rtic :: export :: run ( PRIORITY , | | { crate :: gpioa ( gpioa :: Context :: new ( & rtic :: export :: Priority :: new ( PRIORITY ) ) ) } ) ; } impl < 'a > gpioaResources < 'a > { # [ inline ( always ) ] unsafe fn new ( priority : & 'a rtic :: export :: Priority ) -> Self { gpioaResources { shared : resources :: shared :: new ( priority ) , } } } # [ allow ( non_snake_case ) ] # [ no_mangle ] unsafe fn GPIOB ( ) { const PRIORITY : u8 = 2u8 ; rtic :: export :: run ( PRIORITY , | | { crate :: gpiob ( gpiob :: Context :: new ( & rtic :: export :: Priority :: new ( PRIORITY ) ) ) } ) ; } impl < 'a > gpiobResources < 'a > { # [ inline ( always ) ] unsafe fn new ( priority : & 'a rtic :: export :: Priority ) -> Self { gpiobResources { shared : & mut shared , } } } # [ no_mangle ] unsafe extern "C" fn main ( ) -> ! { let _TODO : ( ) = ( ) ; rtic :: export :: interrupt :: disable ( ) ; let mut core : rtic :: export :: Peripherals = core :: mem :: transmute ( ( ) ) ; let _ = [ ( ) ; ( ( 1 << lm3s6965 :: NVIC_PRIO_BITS ) - 1u8 as usize ) ] ; core . NVIC . set_priority ( lm3s6965 :: Interrupt :: GPIOA , rtic :: export :: logical2hw ( 1u8 , lm3s6965 :: NVIC_PRIO_BITS ) ) ; rtic :: export :: NVIC :: unmask ( lm3s6965 :: Interrupt :: GPIOA ) ; let _ = [ ( ) ; ( ( 1 << lm3s6965 :: NVIC_PRIO_BITS ) - 2u8 as usize ) ] ; core . NVIC . set_priority ( lm3s6965 :: Interrupt :: GPIOB , rtic :: export :: logical2hw ( 2u8 , lm3s6965 :: NVIC_PRIO_BITS ) ) ; rtic :: export :: NVIC :: unmask ( lm3s6965 :: Interrupt :: GPIOB ) ; core . SCB . scr . modify ( | r | r | 1 << 1 ) ; let late = crate :: init ( init :: Context :: new ( core . into ( ) ) ) ; rtic :: export :: interrupt :: enable ( ) ; loop { rtic :: export :: wfi ( ) } } };
diff --git a/expand_lock2.rs b/expand_lock2.rs
new file mode 100644
index 0000000000..43052a2312
--- /dev/null
+++ b/expand_lock2.rs
@@ -0,0 +1,153 @@
+#![feature(prelude_import)]
+//! examples/lock2.rs
+#![deny(unsafe_code)]
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+#[prelude_import]
+use core::prelude::v1::*;
+#[macro_use]
+extern crate core;
+#[macro_use]
+extern crate compiler_builtins;
+use cortex_m_semihosting::debug;
+use lm3s6965::Interrupt;
+#[allow(non_snake_case)]
+fn init(_: init::Context) {
+    rtic::pend(Interrupt::GPIOA);
+}
+#[allow(non_snake_case)]
+fn gpioa(mut c: gpioa::Context) {
+    use rtic::Mutex as _;
+    c.resources.shared.lock(|shared| {
+        *shared += 1;
+        rtic::pend(Interrupt::GPIOB);
+    });
+    debug::exit(debug::EXIT_SUCCESS);
+}
+#[allow(non_snake_case)]
+fn gpiob(c: gpiob::Context) {
+    use rtic::Mutex as _;
+    *c.resources.shared += 1;
+}
+#[allow(non_snake_case)]
+///Initialization function
+pub mod init {
+    /// Execution context
+    pub struct Context {
+        /// Core (Cortex-M) peripherals
+        pub core: rtic::export::Peripherals,
+    }
+    impl Context {
+        #[inline(always)]
+        pub unsafe fn new(core: rtic::export::Peripherals) -> Self {
+            Context { core }
+        }
+    }
+}
+mod resources {
+    use rtic::export::Priority;
+    use core::cell::Cell;
+    #[allow(non_camel_case_types)]
+    pub struct shared<'a> {
+        priority: &'a Priority,
+        locked: Cell<bool>,
+    }
+    impl<'a> shared<'a> {
+        #[inline(always)]
+        pub unsafe fn new(priority: &'a Priority) -> Self {
+            shared {
+                priority,
+                locked: Cell::new(false),
+            }
+        }
+        #[inline(always)]
+        pub unsafe fn priority(&self) -> &Priority {
+            self.priority
+        }
+        #[inline(always)]
+        pub unsafe fn is_locked(&self) -> bool {
+            self.locked.get()
+        }
+        pub unsafe fn lock(&self) {
+            self.locked.set(true);
+        }
+    }
+    #[allow(non_camel_case_types)]
+    pub struct shared2<'a> {
+        priority: &'a Priority,
+        locked: Cell<bool>,
+    }
+    impl<'a> shared2<'a> {
+        #[inline(always)]
+        pub unsafe fn new(priority: &'a Priority) -> Self {
+            shared2 {
+                priority,
+                locked: Cell::new(false),
+            }
+        }
+        #[inline(always)]
+        pub unsafe fn priority(&self) -> &Priority {
+            self.priority
+        }
+        #[inline(always)]
+        pub unsafe fn is_locked(&self) -> bool {
+            self.locked.get()
+        }
+        pub unsafe fn lock(&self) {
+            self.locked.set(true);
+        }
+    }
+}
+#[allow(non_snake_case)]
+///Resources `gpioa` has access to
+pub struct gpioaResources<'a> {
+    pub shared: resources::shared<'a>,
+    pub shared2: resources::shared2<'a>,
+}
+#[allow(non_snake_case)]
+///Hardware task
+pub mod gpioa {
+    #[doc(inline)]
+    pub use super::gpioaResources as Resources;
+    /// Execution context
+    pub struct Context<'a> {
+        /// Resources this task has access to
+        pub resources: Resources<'a>,
+    }
+    impl<'a> Context<'a> {
+        #[inline(always)]
+        pub unsafe fn new(priority: &'a rtic::export::Priority) -> Self {
+            Context {
+                resources: Resources::new(priority),
+            }
+        }
+    }
+}
+#[allow(non_snake_case)]
+///Resources `gpiob` has access to
+pub struct gpiobResources<'a> {
+    pub shared: &'a mut u32,
+    pub shared2: &'a mut u32,
+}
+#[allow(non_snake_case)]
+///Hardware task
+pub mod gpiob {
+    #[doc(inline)]
+    pub use super::gpiobResources as Resources;
+    /// Execution context
+    pub struct Context<'a> {
+        /// Resources this task has access to
+        pub resources: Resources<'a>,
+    }
+    impl<'a> Context<'a> {
+        #[inline(always)]
+        pub unsafe fn new(priority: &'a rtic::export::Priority) -> Self {
+            Context {
+                resources: Resources::new(priority),
+            }
+        }
+    }
+}
+/// Implementation details
+const APP: () = { # [ doc = r" Always include the device crate which contains the vector table" ] use lm3s6965 as _ ; # [ allow ( non_upper_case_globals ) ] static mut shared : u32 = 0 ; impl < 'a > rtic :: Mutex for resources :: shared < 'a > { type T = u32 ; # [ inline ( always ) ] fn lock < R > ( & mut self , f : impl FnOnce ( & mut u32 ) -> R ) -> R { # [ doc = r" Priority ceiling" ] const CEILING : u8 = 2u8 ; unsafe { rtic :: export :: lock ( & mut shared , self . priority ( ) , CEILING , lm3s6965 :: NVIC_PRIO_BITS , f ) } } } # [ allow ( non_upper_case_globals ) ] static mut shared2 : u32 = 0 ; impl < 'a > rtic :: Mutex for resources :: shared2 < 'a > { type T = u32 ; # [ inline ( always ) ] fn lock < R > ( & mut self , f : impl FnOnce ( & mut u32 ) -> R ) -> R { # [ doc = r" Priority ceiling" ] const CEILING : u8 = 2u8 ; unsafe { rtic :: export :: lock ( & mut shared2 , self . priority ( ) , CEILING , lm3s6965 :: NVIC_PRIO_BITS , f ) } } } # [ allow ( non_snake_case ) ] # [ no_mangle ] unsafe fn GPIOA ( ) { const PRIORITY : u8 = 1u8 ; rtic :: export :: run ( PRIORITY , | | { crate :: gpioa ( gpioa :: Context :: new ( & rtic :: export :: Priority :: new ( PRIORITY ) ) ) } ) ; } impl < 'a > gpioaResources < 'a > { # [ inline ( always ) ] unsafe fn new ( priority : & 'a rtic :: export :: Priority ) -> Self { gpioaResources { shared : resources :: shared :: new ( priority ) , shared2 : resources :: shared2 :: new ( priority ) , } } } # [ allow ( non_snake_case ) ] # [ no_mangle ] unsafe fn GPIOB ( ) { const PRIORITY : u8 = 2u8 ; rtic :: export :: run ( PRIORITY , | | { crate :: gpiob ( gpiob :: Context :: new ( & rtic :: export :: Priority :: new ( PRIORITY ) ) ) } ) ; } impl < 'a > gpiobResources < 'a > { # [ inline ( always ) ] unsafe fn new ( priority : & 'a rtic :: export :: Priority ) -> Self { gpiobResources { shared : & mut shared , shared2 : & mut shared2 , } } } # [ no_mangle ] unsafe extern "C" fn main ( ) -> ! { let _TODO : ( ) = ( ) ; rtic :: export :: interrupt :: disable ( ) ; let mut core : rtic :: export :: Peripherals = core :: mem :: transmute ( ( ) ) ; let _ = [ ( ) ; ( ( 1 << lm3s6965 :: NVIC_PRIO_BITS ) - 1u8 as usize ) ] ; core . NVIC . set_priority ( lm3s6965 :: Interrupt :: GPIOA , rtic :: export :: logical2hw ( 1u8 , lm3s6965 :: NVIC_PRIO_BITS ) ) ; rtic :: export :: NVIC :: unmask ( lm3s6965 :: Interrupt :: GPIOA ) ; let _ = [ ( ) ; ( ( 1 << lm3s6965 :: NVIC_PRIO_BITS ) - 2u8 as usize ) ] ; core . NVIC . set_priority ( lm3s6965 :: Interrupt :: GPIOB , rtic :: export :: logical2hw ( 2u8 , lm3s6965 :: NVIC_PRIO_BITS ) ) ; rtic :: export :: NVIC :: unmask ( lm3s6965 :: Interrupt :: GPIOB ) ; core . SCB . scr . modify ( | r | r | 1 << 1 ) ; let late = crate :: init ( init :: Context :: new ( core . into ( ) ) ) ; rtic :: export :: interrupt :: enable ( ) ; loop { rtic :: export :: wfi ( ) } } };
diff --git a/macros/src/codegen/resources.rs b/macros/src/codegen/resources.rs
index 0bec3e5ae6..6788648b39 100644
--- a/macros/src/codegen/resources.rs
+++ b/macros/src/codegen/resources.rs
@@ -83,6 +83,7 @@ pub fn codegen(
                 #cfg_core
                 pub struct #name<'a> {
                     priority: &'a Priority,
+                    locked: Cell<bool>,
                 }
 
                 #(#cfgs)*
@@ -90,13 +91,25 @@ pub fn codegen(
                 impl<'a> #name<'a> {
                     #[inline(always)]
                     pub unsafe fn new(priority: &'a Priority) -> Self {
-                        #name { priority }
+                        #name {
+                            priority,
+                            locked: Cell::new(false),
+                        }
                     }
 
                     #[inline(always)]
                     pub unsafe fn priority(&self) -> &Priority {
                         self.priority
                     }
+
+                    #[inline(always)]
+                    pub unsafe fn is_locked(&self) -> bool {
+                        self.locked.get()
+                    }
+
+                    pub unsafe fn lock(&self) {
+                        self.locked.set(true);
+                    }
                 }
             ));
 
@@ -130,7 +143,7 @@ pub fn codegen(
     } else {
         quote!(mod resources {
             use rtic::export::Priority;
-
+            use core::cell::Cell;
             #(#mod_resources)*
         })
     };