diff --git a/CHANGELOG.md b/CHANGELOG.md
index bd18d12269..b9bd7f5339 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,14 @@ For each category, *Added*, *Changed*, *Fixed* add new entries at the top!
 
 ## [Unreleased]
 
+### Added
+
+### Fixed
+
+- Generation of masks for the source masking scheduling for thumbv6
+
+### Changed
+
 ## [v1.1.1] - 2022-04-13
 
 ### Added
diff --git a/macros/src/codegen/shared_resources.rs b/macros/src/codegen/shared_resources.rs
index a016e4538d..e3109c8285 100644
--- a/macros/src/codegen/shared_resources.rs
+++ b/macros/src/codegen/shared_resources.rs
@@ -1,8 +1,8 @@
+use crate::{analyze::Analysis, check::Extra, codegen::util};
 use proc_macro2::TokenStream as TokenStream2;
 use quote::quote;
 use rtic_syntax::{analyze::Ownership, ast::App};
-
-use crate::{analyze::Analysis, check::Extra, codegen::util};
+use std::collections::HashMap;
 
 /// Generates `static` variables and shared resource proxies
 pub fn codegen(
@@ -108,14 +108,9 @@ pub fn codegen(
     // Computing mapping of used interrupts to masks
     let interrupt_ids = analysis.interrupts.iter().map(|(p, (id, _))| (p, id));
 
-    use std::collections::HashMap;
-    let mut masks: HashMap<u8, _> = std::collections::HashMap::new();
+    let mut prio_to_masks = HashMap::new();
     let device = &extra.device;
 
-    for p in 0..3 {
-        masks.insert(p, quote!(0));
-    }
-
     for (&priority, name) in interrupt_ids.chain(app.hardware_tasks.values().flat_map(|task| {
         if !util::is_exception(&task.args.binds) {
             Some((&task.args.priority, &task.args.binds))
@@ -124,18 +119,31 @@ pub fn codegen(
             None
         }
     })) {
-        let name = quote!(#device::Interrupt::#name as u32);
-        if let Some(v) = masks.get_mut(&(priority - 1)) {
-            *v = quote!(#v | 1 << #name);
-        };
+        let v = prio_to_masks.entry(priority - 1).or_insert(Vec::new());
+        v.push(quote!(#device::Interrupt::#name as u32));
     }
 
-    let mut mask_arr: Vec<(_, _)> = masks.iter().collect();
-    mask_arr.sort_by_key(|(k, _v)| *k);
-    let mask_arr: Vec<_> = mask_arr.iter().map(|(_, v)| v).collect();
+    // Call rtic::export::create_mask([u32; N]), where the array is the list of shifts
 
+    let mut mask_arr = Vec::new();
+    // NOTE: 0..3 assumes max 4 priority levels according to M0 spec
+    for i in 0..3 {
+        let v = if let Some(v) = prio_to_masks.get(&i) {
+            v.clone()
+        } else {
+            Vec::new()
+        };
+
+        mask_arr.push(quote!(
+            rtic::export::create_mask([#(#v),*])
+        ));
+    }
+
+    let masks_name = util::priority_masks_ident();
     mod_app.push(quote!(
-        const MASKS: [u32; 3] = [#(#mask_arr),*];
+        #[doc(hidden)]
+        #[allow(non_camel_case_types)]
+        const #masks_name: [u32; 3] = [#(#mask_arr),*];
     ));
 
     (mod_app, mod_resources)
diff --git a/macros/src/codegen/util.rs b/macros/src/codegen/util.rs
index 4a29754bc8..0f3dca7c47 100644
--- a/macros/src/codegen/util.rs
+++ b/macros/src/codegen/util.rs
@@ -36,6 +36,7 @@ pub fn impl_mutex(
     };
 
     let device = &extra.device;
+    let masks_name = priority_masks_ident();
     quote!(
         #(#cfgs)*
         impl<'a> rtic::Mutex for #path<'a> {
@@ -52,7 +53,7 @@ pub fn impl_mutex(
                         #priority,
                         CEILING,
                         #device::NVIC_PRIO_BITS,
-                        &MASKS,
+                        &#masks_name,
                         f,
                     )
                 }
@@ -252,6 +253,10 @@ pub fn static_shared_resource_ident(name: &Ident) -> Ident {
     mark_internal_name(&format!("shared_resource_{}", name))
 }
 
+pub fn priority_masks_ident() -> Ident {
+    mark_internal_name("MASKS")
+}
+
 pub fn static_local_resource_ident(name: &Ident) -> Ident {
     mark_internal_name(&format!("local_resource_{}", name))
 }
diff --git a/src/export.rs b/src/export.rs
index ed51a9e9f7..035899180a 100644
--- a/src/export.rs
+++ b/src/export.rs
@@ -315,3 +315,27 @@ unsafe fn clear_enable_mask(mask: u32) {
 pub fn logical2hw(logical: u8, nvic_prio_bits: u8) -> u8 {
     ((1 << nvic_prio_bits) - logical) << (8 - nvic_prio_bits)
 }
+
+#[cfg(not(armv6m))]
+pub const fn create_mask<const N: usize>(_: [u32; N]) -> u32 {
+    0
+}
+
+#[cfg(armv6m)]
+pub const fn create_mask<const N: usize>(list_of_shifts: [u32; N]) -> u32 {
+    let mut mask = 0;
+    let mut i = 0;
+
+    while i < N {
+        let shift = list_of_shifts[i];
+        i += 1;
+
+        if shift > 31 {
+            panic!("Generating masks for thumbv6 failed! Are you compiling for thumbv6 on an thumbv7 MCU?");
+        }
+
+        mask |= 1 << shift;
+    }
+
+    mask
+}