diff --git a/services/root-keys/src/implementation.rs b/services/root-keys/src/implementation.rs
index 60fba9232..683295c10 100644
--- a/services/root-keys/src/implementation.rs
+++ b/services/root-keys/src/implementation.rs
@@ -552,7 +552,7 @@ impl RootKeys {
     fn debug_print_key(&self, offset: usize, num_bits: usize, name: &str) {
         use core::fmt::Write;
         let mut debugstr = xous_ipc::String::<4096>::new();
-        let sensitive_slice = self.sensitive_data.as_slice_mut::<u32>();
+        let sensitive_slice = self.sensitive_data.as_slice::<u32>();
         write!(debugstr, "{}", name).unwrap();
         for word in sensitive_slice[offset .. offset as usize + num_bits/(size_of::<u32>()*8)].iter() {
             for byte in word.to_be_bytes().iter() {
@@ -577,7 +577,7 @@ impl RootKeys {
 
         // now get the font plane data
         self.gfx.bulk_read_restart(); // reset the bulk read pointers on the gfx side
-        let mut bulkread = BulkRead::default();
+        let bulkread = BulkRead::default();
         let mut buf = xous_ipc::Buffer::into_buf(bulkread).expect("couldn't transform bulkread into aligned buffer");
         // this form of loop was chosen to avoid the multiple re-initializations and copies that would be entailed
         // in our usual idiom for pasing buffers around. instead, we create a single buffer, and re-use it for
diff --git a/services/shellchat/src/cmds/keys.rs b/services/shellchat/src/cmds/keys.rs
index 9fb9a5416..7537ba0b3 100644
--- a/services/shellchat/src/cmds/keys.rs
+++ b/services/shellchat/src/cmds/keys.rs
@@ -69,7 +69,7 @@ impl<'a> ShellCmdApi<'a> for Keys {
 
                     log::debug!("top of region: {:x?}", &region[0..8]);
                     // a region to stash a copy of the previous data in the testing area, so we can diff to confirm things worked!
-                    let reference_region = xous::syscall::map_memory(
+                    let mut reference_region = xous::syscall::map_memory(
                         None,
                         None,
                         TEST_SIZE,
diff --git a/services/shellchat/src/cmds/memtest.rs b/services/shellchat/src/cmds/memtest.rs
index e3284fa4c..6717c4484 100644
--- a/services/shellchat/src/cmds/memtest.rs
+++ b/services/shellchat/src/cmds/memtest.rs
@@ -52,13 +52,13 @@ pub fn test_thread(sid0: usize, sid1: usize, sid2: usize, sid3: usize) {
         log::debug!("memtest got msg {:?}", msg);
         match FromPrimitive::from_usize(msg.body.id()) {
             Some(TestOp::StartBasic) => xous::msg_scalar_unpack!(msg, iters, _, _, _, {
-                let testsrc = xous::syscall::map_memory(
+                let mut testsrc = xous::syscall::map_memory(
                     None,
                     None,
                     256 * 1024, // min 128k so we are working through the L2 cache
                     xous::MemoryFlags::R | xous::MemoryFlags::W | xous::MemoryFlags::RESERVE,
                 ).expect("couldn't allocate RAM for testing");
-                let testdst = xous::syscall::map_memory(
+                let mut testdst = xous::syscall::map_memory(
                     None,
                     None,
                     256 * 1024,