diff --git a/crates/namada/src/vm/memory.rs b/crates/namada/src/vm/memory.rs
index e55117726c..fe53a6c832 100644
--- a/crates/namada/src/vm/memory.rs
+++ b/crates/namada/src/vm/memory.rs
@@ -9,28 +9,28 @@ pub trait VmMemory: Clone + Send + Sync {
 
     /// Returns bytes read from memory together with the associated gas cost.
     fn read_bytes(
-        &self,
+        &mut self,
         offset: u64,
         len: usize,
     ) -> Result<(Vec<u8>, u64), Self::Error>;
 
     /// Write bytes to memory. Returns the gas cost.
     fn write_bytes(
-        &self,
+        &mut self,
         offset: u64,
         bytes: impl AsRef<[u8]>,
     ) -> Result<u64, Self::Error>;
 
     /// Returns string read from memory together with the associated gas cost.
     fn read_string(
-        &self,
+        &mut self,
         offset: u64,
         len: usize,
     ) -> Result<(String, u64), Self::Error>;
 
     /// Write string to memory. Returns the gas cost.
     fn write_string(
-        &self,
+        &mut self,
         offset: u64,
         string: String,
     ) -> Result<u64, Self::Error>;
@@ -55,7 +55,7 @@ pub mod testing {
         type Error = Infallible;
 
         fn read_bytes(
-            &self,
+            &mut self,
             offset: u64,
             len: usize,
         ) -> Result<(Vec<u8>, u64)> {
@@ -64,7 +64,7 @@ pub mod testing {
         }
 
         fn write_bytes(
-            &self,
+            &mut self,
             offset: u64,
             bytes: impl AsRef<[u8]>,
         ) -> Result<u64> {
@@ -77,7 +77,7 @@ pub mod testing {
         }
 
         fn read_string(
-            &self,
+            &mut self,
             offset: u64,
             len: usize,
         ) -> Result<(String, u64)> {
@@ -88,7 +88,7 @@ pub mod testing {
             Ok((string, 0))
         }
 
-        fn write_string(&self, offset: u64, string: String) -> Result<u64> {
+        fn write_string(&mut self, offset: u64, string: String) -> Result<u64> {
             let bytes = string.as_bytes();
             let len = bytes.len();
             let target =
diff --git a/crates/namada/src/vm/wasm/memory.rs b/crates/namada/src/vm/wasm/memory.rs
index 89ebcd037f..6cd7bbf924 100644
--- a/crates/namada/src/vm/wasm/memory.rs
+++ b/crates/namada/src/vm/wasm/memory.rs
@@ -311,7 +311,11 @@ impl VmMemory for WasmMemory {
 
     /// Read bytes from memory at the given offset and length, return the bytes
     /// and the gas cost
-    fn read_bytes(&self, offset: u64, len: usize) -> Result<(Vec<u8>, u64)> {
+    fn read_bytes(
+        &mut self,
+        offset: u64,
+        len: usize,
+    ) -> Result<(Vec<u8>, u64)> {
         self.access(|memory| {
             let mut store = self.store.borrow_mut();
             let bytes = read_memory_bytes(&mut *store, memory, offset, len)?;
@@ -322,7 +326,11 @@ impl VmMemory for WasmMemory {
     }
 
     /// Write bytes into memory at the given offset and return the gas cost
-    fn write_bytes(&self, offset: u64, bytes: impl AsRef<[u8]>) -> Result<u64> {
+    fn write_bytes(
+        &mut self,
+        offset: u64,
+        bytes: impl AsRef<[u8]>,
+    ) -> Result<u64> {
         self.access(|memory| {
             // No need for a separate gas multiplier for writes since we are
             // only writing to memory and we already charge gas for
@@ -337,7 +345,11 @@ impl VmMemory for WasmMemory {
 
     /// Read string from memory at the given offset and bytes length, and return
     /// the gas cost
-    fn read_string(&self, offset: u64, len: usize) -> Result<(String, u64)> {
+    fn read_string(
+        &mut self,
+        offset: u64,
+        len: usize,
+    ) -> Result<(String, u64)> {
         let (bytes, gas) = self.read_bytes(offset, len)?;
         let string = std::str::from_utf8(&bytes)
             .map_err(Error::InvalidUtf8String)?
@@ -347,7 +359,7 @@ impl VmMemory for WasmMemory {
 
     /// Write string into memory at the given offset and return the gas cost
     #[allow(dead_code)]
-    fn write_string(&self, offset: u64, string: String) -> Result<u64> {
+    fn write_string(&mut self, offset: u64, string: String) -> Result<u64> {
         self.write_bytes(offset, string.as_bytes())
     }
 }
diff --git a/crates/tests/src/vm_host_env/tx.rs b/crates/tests/src/vm_host_env/tx.rs
index 7df8beb282..594391024d 100644
--- a/crates/tests/src/vm_host_env/tx.rs
+++ b/crates/tests/src/vm_host_env/tx.rs
@@ -759,7 +759,7 @@ mod tests {
             batched_tx,
         } = test_env;
 
-        let tx_env = vm::host_env::testing::tx_env_with_wasm_memory(
+        let mut tx_env = vm::host_env::testing::tx_env_with_wasm_memory(
             state,
             iterators,
             verifiers,