diff --git a/Cargo.toml b/Cargo.toml
index 9bd417b16..46dfad647 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -91,7 +91,7 @@ getrandom = { version = "0.2.16" }
 itertools = { version = "0.14", default-features = false }
 miette = { version = "7.6.0", features = ["fancy"] }
 hashbrown = { version = "0.16.1", features = ["serde"] }
-core2 = { version = "0.4.0", default-features = false, features = ["alloc"] }
+no_std_io2 = { git = "https://github.com/ergoplatform/no-std-io2", rev = "68dbe54373c7d884b7a8a2e02fb0b734dbd590cc", default-features = false, features = ["alloc"] }
 # dev-dependencies
 proptest = { version = "=1.6.0", default-features = false, features = [
     "alloc",
diff --git a/ergo-chain-types/Cargo.toml b/ergo-chain-types/Cargo.toml
index 9b53fd23a..c59c74b39 100644
--- a/ergo-chain-types/Cargo.toml
+++ b/ergo-chain-types/Cargo.toml
@@ -26,7 +26,7 @@ serde_with = { workspace = true, optional = true }
 proptest = { workspace = true, optional = true }
 proptest-derive = { workspace = true, optional = true }
 num-traits = { workspace = true }
-core2 = { workspace = true }
+no_std_io2 = { workspace = true }
 
 [features]
 default = ["std", "json"]
diff --git a/ergo-chain-types/src/header.rs b/ergo-chain-types/src/header.rs
index 44d40b3f4..b03c216a0 100644
--- a/ergo-chain-types/src/header.rs
+++ b/ergo-chain-types/src/header.rs
@@ -5,7 +5,7 @@ use crate::autolykos_pow_scheme::{
 use crate::{ADDigest, BlockId, Digest32, EcPoint};
 use alloc::boxed::Box;
 use alloc::vec::Vec;
-use core2::io::Write;
+use no_std_io2::io::Write;
 use num_bigint::{BigUint, ToBigInt};
 use sigma_ser::vlq_encode::{ReadSigmaVlqExt, WriteSigmaVlqExt};
 use sigma_ser::{
diff --git a/ergotree-interpreter/Cargo.toml b/ergotree-interpreter/Cargo.toml
index af1df292e..5cb1232d0 100644
--- a/ergotree-interpreter/Cargo.toml
+++ b/ergotree-interpreter/Cargo.toml
@@ -38,7 +38,7 @@ ergo_avltree_rust = { version = "0.1.1" }
 gf2_192 = { version = "^0.28.0", path = "../gf2_192" }
 miette = { workspace = true, optional = true }
 hashbrown = { workspace = true }
-core2 = { workspace = true }
+no_std_io2 = { workspace = true }
 sigma-test-util = { workspace = true, optional = true }
 
 generic-array = "=0.14.7" #TODO: unpin this when k256 and elliptic-curve upgrade to generic-array 1.0 and remove the deprecation warnings
diff --git a/ergotree-interpreter/src/sigma_protocol/challenge.rs b/ergotree-interpreter/src/sigma_protocol/challenge.rs
index 9bb150395..1ccd210e9 100644
--- a/ergotree-interpreter/src/sigma_protocol/challenge.rs
+++ b/ergotree-interpreter/src/sigma_protocol/challenge.rs
@@ -37,12 +37,15 @@ impl Challenge {
         FiatShamirHash::try_from(res.as_slice()).unwrap().into()
     }
 
-    pub fn sigma_serialize<W: SigmaByteWrite>(&self, w: &mut W) -> Result<(), core2::io::Error> {
+    pub fn sigma_serialize<W: SigmaByteWrite>(
+        &self,
+        w: &mut W,
+    ) -> Result<(), no_std_io2::io::Error> {
         w.write_all(self.0 .0.as_ref())?;
         Ok(())
     }
 
-    pub fn sigma_parse<R: SigmaByteRead>(r: &mut R) -> Result<Self, core2::io::Error> {
+    pub fn sigma_parse<R: SigmaByteRead>(r: &mut R) -> Result<Self, no_std_io2::io::Error> {
         let mut chal_bytes: [u8; super::SOUNDNESS_BYTES] = [0; super::SOUNDNESS_BYTES];
         r.read_exact(&mut chal_bytes)?;
         Ok(Challenge::from(FiatShamirHash(Box::new(chal_bytes))))
diff --git a/ergotree-interpreter/src/sigma_protocol/fiat_shamir.rs b/ergotree-interpreter/src/sigma_protocol/fiat_shamir.rs
index 288b8e06b..0fb95d4c8 100644
--- a/ergotree-interpreter/src/sigma_protocol/fiat_shamir.rs
+++ b/ergotree-interpreter/src/sigma_protocol/fiat_shamir.rs
@@ -130,8 +130,8 @@ pub enum FiatShamirTreeSerializationError {
     IoError(String),
 }
 
-impl From<core2::io::Error> for FiatShamirTreeSerializationError {
-    fn from(error: core2::io::Error) -> FiatShamirTreeSerializationError {
+impl From<no_std_io2::io::Error> for FiatShamirTreeSerializationError {
+    fn from(error: no_std_io2::io::Error) -> FiatShamirTreeSerializationError {
         FiatShamirTreeSerializationError::IoError(error.to_string())
     }
 }
diff --git a/ergotree-interpreter/src/sigma_protocol/sig_serializer.rs b/ergotree-interpreter/src/sigma_protocol/sig_serializer.rs
index c6e296425..d0c8dd0af 100644
--- a/ergotree-interpreter/src/sigma_protocol/sig_serializer.rs
+++ b/ergotree-interpreter/src/sigma_protocol/sig_serializer.rs
@@ -49,7 +49,7 @@ fn sig_write_bytes<W: SigmaByteWrite>(
     node: &UncheckedTree,
     w: &mut W,
     write_challenges: bool,
-) -> Result<(), core2::io::Error> {
+) -> Result<(), no_std_io2::io::Error> {
     if write_challenges {
         node.challenge().sigma_serialize(w)?;
     }
@@ -289,7 +289,7 @@ pub enum SigParsingError {
 #[cfg(test)]
 #[allow(clippy::unwrap_used)]
 mod test {
-    use core2::io::Cursor;
+    use no_std_io2::io::Cursor;
 
     use ergotree_ir::serialization::{
         constant_store::ConstantStore, sigma_byte_reader::SigmaByteReader,
diff --git a/ergotree-ir/Cargo.toml b/ergotree-ir/Cargo.toml
index 4c2443d48..9729809bc 100644
--- a/ergotree-ir/Cargo.toml
+++ b/ergotree-ir/Cargo.toml
@@ -39,7 +39,7 @@ strum = { version = "0.27.2", default-features = false, features = ["derive"] }
 strum_macros = { version = "0.27.2", default-features = false }
 miette = { workspace = true, optional = true }
 hashbrown = { workspace = true }
-core2 = { workspace = true }
+no_std_io2 = { workspace = true }
 foldhash = { version = "0.2.0", default-features = false }
 [features]
 default = ["json", "std"]
@@ -52,7 +52,7 @@ json = [
     "ergo-chain-types/json",
     "indexmap/serde",
 ]
-std = ["core2/std", "dep:miette", "ergo-chain-types/std", "sigma-ser/std"]
+std = ["no_std_io2/std", "dep:miette", "ergo-chain-types/std", "sigma-ser/std"]
 
 [dev-dependencies]
 sigma-test-util = { workspace = true }
diff --git a/ergotree-ir/src/ergo_tree.rs b/ergotree-ir/src/ergo_tree.rs
index a1d52708d..bfaf721b0 100644
--- a/ergotree-ir/src/ergo_tree.rs
+++ b/ergotree-ir/src/ergo_tree.rs
@@ -20,9 +20,9 @@ use sigma_ser::vlq_encode::WriteSigmaVlqExt;
 
 use crate::serialization::constant_store::ConstantStore;
 use core::convert::TryFrom;
-use core2::io;
 use derive_more::From;
 use io::Cursor;
+use no_std_io2::io;
 #[cfg(feature = "std")]
 use std::sync::OnceLock;
 use thiserror::Error;
@@ -440,8 +440,8 @@ impl TryFrom<ErgoTree> for ProveDlog {
     }
 }
 
-impl From<core2::io::Error> for ErgoTreeError {
-    fn from(e: core2::io::Error) -> Self {
+impl From<no_std_io2::io::Error> for ErgoTreeError {
+    fn from(e: no_std_io2::io::Error) -> Self {
         ErgoTreeError::IoError(e.to_string())
     }
 }
diff --git a/ergotree-ir/src/ergo_tree/tree_header.rs b/ergotree-ir/src/ergo_tree/tree_header.rs
index 67e1779e7..07f431fae 100644
--- a/ergotree-ir/src/ergo_tree/tree_header.rs
+++ b/ergotree-ir/src/ergo_tree/tree_header.rs
@@ -33,7 +33,10 @@ pub struct ErgoTreeHeader {
 
 impl ErgoTreeHeader {
     /// Serialization
-    pub fn sigma_serialize<W: SigmaByteWrite>(&self, w: &mut W) -> Result<(), core2::io::Error> {
+    pub fn sigma_serialize<W: SigmaByteWrite>(
+        &self,
+        w: &mut W,
+    ) -> Result<(), no_std_io2::io::Error> {
         w.put_u8(self.serialized())
     }
     /// Deserialization
diff --git a/ergotree-ir/src/mir/val_def.rs b/ergotree-ir/src/mir/val_def.rs
index 38e56da96..91a2e241d 100644
--- a/ergotree-ir/src/mir/val_def.rs
+++ b/ergotree-ir/src/mir/val_def.rs
@@ -24,7 +24,10 @@ use proptest_derive::Arbitrary;
 pub struct ValId(pub u32);
 
 impl ValId {
-    pub(crate) fn sigma_serialize<W: SigmaByteWrite>(&self, w: &mut W) -> core2::io::Result<()> {
+    pub(crate) fn sigma_serialize<W: SigmaByteWrite>(
+        &self,
+        w: &mut W,
+    ) -> no_std_io2::io::Result<()> {
         w.put_u32(self.0)
     }
 
diff --git a/ergotree-ir/src/serialization/constant_placeholder.rs b/ergotree-ir/src/serialization/constant_placeholder.rs
index b8dbf57c2..b78235e92 100644
--- a/ergotree-ir/src/serialization/constant_placeholder.rs
+++ b/ergotree-ir/src/serialization/constant_placeholder.rs
@@ -38,7 +38,7 @@ mod tests {
     };
 
     use alloc::vec::Vec;
-    use core2::io::Cursor;
+    use no_std_io2::io::Cursor;
     use proptest::prelude::*;
 
     proptest! {
diff --git a/ergotree-ir/src/serialization/serializable.rs b/ergotree-ir/src/serialization/serializable.rs
index 3745aaf01..2ee477739 100644
--- a/ergotree-ir/src/serialization/serializable.rs
+++ b/ergotree-ir/src/serialization/serializable.rs
@@ -18,8 +18,8 @@ use alloc::vec::Vec;
 use bounded_vec::BoundedVec;
 use bounded_vec::BoundedVecOutOfBounds;
 use core::convert::TryInto;
-use core2::io;
 use io::Cursor;
+use no_std_io2::io;
 use sigma_ser::{vlq_encode, ScorexParsingError, ScorexSerializationError};
 use thiserror::Error;
 
diff --git a/ergotree-ir/src/serialization/sigma_byte_reader.rs b/ergotree-ir/src/serialization/sigma_byte_reader.rs
index 199eeb5c6..740231ba2 100644
--- a/ergotree-ir/src/serialization/sigma_byte_reader.rs
+++ b/ergotree-ir/src/serialization/sigma_byte_reader.rs
@@ -3,9 +3,9 @@ use crate::ergo_tree::ErgoTreeVersion;
 
 use super::constant_store::ConstantStore;
 use super::val_def_type_store::ValDefTypeStore;
-use core2::io::Cursor;
-use core2::io::Read;
-use core2::io::Seek;
+use no_std_io2::io::Cursor;
+use no_std_io2::io::Read;
+use no_std_io2::io::Seek;
 use sigma_ser::vlq_encode::ReadSigmaVlqExt;
 
 /// Implementation of SigmaByteRead
@@ -74,14 +74,14 @@ pub trait SigmaByteRead: ReadSigmaVlqExt {
     fn set_deserialize(&mut self, has_deserialize: bool);
 
     /// Get position of reader in buffer. This is functionally equivalent to [`std::io::Seek::stream_position`] but redefined here so it can be used in no_std contexts
-    fn position(&mut self) -> core2::io::Result<u64> {
+    fn position(&mut self) -> no_std_io2::io::Result<u64> {
         #[cfg(feature = "std")]
         {
             <Self as Seek>::stream_position(self)
         }
         #[cfg(not(feature = "std"))]
         {
-            self.seek(core2::io::SeekFrom::Current(0))
+            self.seek(no_std_io2::io::SeekFrom::Current(0))
         }
     }
 
@@ -97,23 +97,23 @@ pub trait SigmaByteRead: ReadSigmaVlqExt {
 }
 
 impl<R: Read> Read for SigmaByteReader<R> {
-    fn read(&mut self, buf: &mut [u8]) -> core2::io::Result<usize> {
+    fn read(&mut self, buf: &mut [u8]) -> no_std_io2::io::Result<usize> {
         self.inner.read(buf)
     }
 }
 
 impl<R: Seek> Seek for SigmaByteReader<R> {
-    fn seek(&mut self, pos: core2::io::SeekFrom) -> core2::io::Result<u64> {
+    fn seek(&mut self, pos: no_std_io2::io::SeekFrom) -> no_std_io2::io::Result<u64> {
         self.inner.seek(pos)
     }
 
     #[cfg(feature = "std")]
-    fn rewind(&mut self) -> core2::io::Result<()> {
+    fn rewind(&mut self) -> no_std_io2::io::Result<()> {
         self.inner.rewind()
     }
 
     #[cfg(feature = "std")]
-    fn stream_position(&mut self) -> core2::io::Result<u64> {
+    fn stream_position(&mut self) -> no_std_io2::io::Result<u64> {
         self.inner.stream_position()
     }
 }
diff --git a/ergotree-ir/src/serialization/sigma_byte_writer.rs b/ergotree-ir/src/serialization/sigma_byte_writer.rs
index bd186cac5..42bac93a9 100644
--- a/ergotree-ir/src/serialization/sigma_byte_writer.rs
+++ b/ergotree-ir/src/serialization/sigma_byte_writer.rs
@@ -2,7 +2,7 @@
 use crate::ergo_tree::ErgoTreeVersion;
 
 use super::constant_store::ConstantStore;
-use core2::io::Write;
+use no_std_io2::io::Write;
 use sigma_ser::vlq_encode::WriteSigmaVlqExt;
 
 /// Implementation for SigmaByteWrite
@@ -39,11 +39,11 @@ pub trait SigmaByteWrite: WriteSigmaVlqExt {
 }
 
 impl<'a, W: Write> Write for SigmaByteWriter<'a, W> {
-    fn write(&mut self, buf: &[u8]) -> core2::io::Result<usize> {
+    fn write(&mut self, buf: &[u8]) -> no_std_io2::io::Result<usize> {
         self.inner.write(buf)
     }
 
-    fn flush(&mut self) -> core2::io::Result<()> {
+    fn flush(&mut self) -> no_std_io2::io::Result<()> {
         self.inner.flush()
     }
 }
diff --git a/ergotree-ir/src/types/smethod.rs b/ergotree-ir/src/types/smethod.rs
index a46dd267b..c67008d5e 100644
--- a/ergotree-ir/src/types/smethod.rs
+++ b/ergotree-ir/src/types/smethod.rs
@@ -22,11 +22,14 @@ use crate::serialization::SigmaParsingError::UnknownMethodId;
 pub struct MethodId(pub u8);
 
 impl MethodId {
-    pub(crate) fn sigma_serialize<W: SigmaByteWrite>(&self, w: &mut W) -> core2::io::Result<()> {
+    pub(crate) fn sigma_serialize<W: SigmaByteWrite>(
+        &self,
+        w: &mut W,
+    ) -> no_std_io2::io::Result<()> {
         w.put_u8(self.0)
     }
 
-    pub(crate) fn sigma_parse<R: SigmaByteRead>(r: &mut R) -> core2::io::Result<Self> {
+    pub(crate) fn sigma_parse<R: SigmaByteRead>(r: &mut R) -> no_std_io2::io::Result<Self> {
         Ok(Self(r.get_u8()?))
     }
 }
diff --git a/sigma-ser/Cargo.toml b/sigma-ser/Cargo.toml
index e33893620..b798da529 100644
--- a/sigma-ser/Cargo.toml
+++ b/sigma-ser/Cargo.toml
@@ -9,13 +9,13 @@ description = "Ergo binary serialization primitives"
 
 [features]
 default = ["std"]
-std = ["core2/std"]
+std = ["no_std_io2/std"]
 
 [dependencies]
 thiserror = { workspace = true }
 bitvec = { workspace = true }
 bounded-vec = { workspace = true }
-core2 = { workspace = true }
+no_std_io2 = { workspace = true }
 
 [dev-dependencies]
 proptest = { workspace = true }
diff --git a/sigma-ser/src/scorex_serialize.rs b/sigma-ser/src/scorex_serialize.rs
index f1c76ddbf..3bfa16080 100644
--- a/sigma-ser/src/scorex_serialize.rs
+++ b/sigma-ser/src/scorex_serialize.rs
@@ -3,8 +3,8 @@ use alloc::string::ToString;
 use alloc::vec::Vec;
 use alloc::{string::String, vec};
 use core::convert::TryInto;
-use core2::io;
-use core2::io::Cursor;
+use no_std_io2::io;
+use no_std_io2::io::Cursor;
 
 use crate::vlq_encode;
 use crate::vlq_encode::*;
diff --git a/sigma-ser/src/vlq_encode.rs b/sigma-ser/src/vlq_encode.rs
index 880e7dc50..034aeb612 100644
--- a/sigma-ser/src/vlq_encode.rs
+++ b/sigma-ser/src/vlq_encode.rs
@@ -5,7 +5,7 @@ use alloc::{
     vec::Vec,
 };
 use core::convert::TryFrom;
-use core2::io;
+use no_std_io2::io;
 
 use bitvec::order::Lsb0;
 use bitvec::prelude::BitVec;
@@ -276,9 +276,9 @@ mod tests {
     use super::*;
     use alloc::format;
     use alloc::vec;
-    use core2::io::Cursor;
-    use core2::io::Read;
-    use core2::io::Write;
+    use no_std_io2::io::Cursor;
+    use no_std_io2::io::Read;
+    use no_std_io2::io::Write;
     use proptest::collection;
 
     extern crate derive_more;