diff --git a/.github/workflows/pr.yml b/.github/workflows/pr.yml
index 8d7cdafc8..dd12ccb93 100644
--- a/.github/workflows/pr.yml
+++ b/.github/workflows/pr.yml
@@ -78,6 +78,19 @@ jobs:
           cd "$GITHUB_WORKSPACE/tools/test-env"
           ./build_zisk.sh
 
+      - name: Check libziskos.a does not bundle std
+        run: |
+          cargo +zisk build -p ziskos --release \
+            --target riscv64ima-zisk-zkvm-elf \
+            --config 'profile.release.lto="fat"'
+          LIBZISKOS=$(find target -name "libziskos.a" -path "*riscv64ima*" | head -1)
+          if ar t "$LIBZISKOS" | grep -q std; then
+            echo "FAIL: libziskos.a contains std object files:"
+            ar t "$LIBZISKOS" | grep std
+            exit 1
+          fi
+          echo "OK: libziskos.a contains no std object files"
+
       - name: Build setup
         env:
           USE_CACHE_SETUP: "1"
diff --git a/definitions/src/lib.rs b/definitions/src/lib.rs
index e90181091..ec211f733 100644
--- a/definitions/src/lib.rs
+++ b/definitions/src/lib.rs
@@ -1,3 +1,5 @@
+#![no_std]
+
 mod syscall;
 pub use syscall::*;
 
diff --git a/ziskos/entrypoint/src/lib.rs b/ziskos/entrypoint/src/lib.rs
index 2918a0356..25e356802 100644
--- a/ziskos/entrypoint/src/lib.rs
+++ b/ziskos/entrypoint/src/lib.rs
@@ -1,4 +1,6 @@
 #![cfg_attr(all(target_os = "zkvm", target_vendor = "zisk"), no_std)]
+#![cfg_attr(all(target_os = "zkvm", target_vendor = "zisk"), feature(core_intrinsics))]
+#![cfg_attr(all(target_os = "zkvm", target_vendor = "zisk"), allow(internal_features))]
 #![allow(unexpected_cfgs)]
 #![allow(unused_imports)]
 
@@ -457,4 +459,13 @@ pub mod ziskos {
     core::arch::global_asm!(include_str!("dma/memcmp.s"));
     //core::arch::global_asm!(include_str!("dma/inputcpy.s"));
     core::arch::global_asm!(include_str!("dma/memset.s"));
+
+    #[panic_handler]
+    fn panic(info: &core::panic::PanicInfo) -> ! {
+        if let Some(msg) = info.message().as_str() {
+            sys_write(1, msg.as_ptr(), msg.len());
+            sys_write(1, b"\n".as_ptr(), 1);
+        }
+        core::intrinsics::abort()
+    }
 }
diff --git a/ziskos/entrypoint/src/zisklib/lib/bn254/curve.rs b/ziskos/entrypoint/src/zisklib/lib/bn254/curve.rs
index db3e5925d..cb25d9f53 100644
--- a/ziskos/entrypoint/src/zisklib/lib/bn254/curve.rs
+++ b/ziskos/entrypoint/src/zisklib/lib/bn254/curve.rs
@@ -3,9 +3,6 @@
 #[cfg(all(target_os = "zkvm", target_vendor = "zisk"))]
 use crate::alloc_extern::vec::Vec;
 
-#[cfg(not(all(target_os = "zkvm", target_vendor = "zisk")))]
-use num_traits::ops::bytes;
-
 use crate::{
     syscalls::{
         syscall_bn254_curve_add, syscall_bn254_curve_dbl, SyscallBn254CurveAddParams,
diff --git a/zkvm-interface/build.rs b/zkvm-interface/build.rs
index cfe0ce2f3..79fffcc9b 100644
--- a/zkvm-interface/build.rs
+++ b/zkvm-interface/build.rs
@@ -10,6 +10,7 @@ fn main() {
         .header(&accelerators_header)
         .header(&io_header)
         .clang_arg("-std=c11")
+        .use_core()
         .allowlist_type("zkvm_.*")
         .allowlist_var("ZKVM_.*")
         .allowlist_function("^zkvm_.*|^read_input$|^write_output$")
diff --git a/zkvm-interface/src/lib.rs b/zkvm-interface/src/lib.rs
index d13c36a11..ec88ab255 100644
--- a/zkvm-interface/src/lib.rs
+++ b/zkvm-interface/src/lib.rs
@@ -1,3 +1,4 @@
+#![no_std]
 //! zkVM C Interface Bindings
 //!
 //! This crate provides Rust bindings generated by bindgen from the standard zkVM