diff --git a/Cargo.toml b/Cargo.toml
index 3d9383f..a1c42ff 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -10,17 +10,6 @@ description = "WebAssembly interpreter"
 keywords = ["wasm", "webassembly", "bytecode", "interpreter"]
 exclude = [ "/res/*", "/tests/*", "/fuzz/*", "/benches/*" ]
 
-[features]
-default = ["std"]
-# Disable for no_std support
-std = [
-    "parity-wasm/std",
-    "wasmi-validation/std",
-]
-# Enable for no_std support
-# hashbrown only works on no_std
-core = ["hashbrown/nightly", "libm"]
-
 [dependencies]
 wasmi-validation = { path = "validation", default-features = false }
 parity-wasm = { version = "0.31", default-features = false }
@@ -33,5 +22,20 @@ assert_matches = "1.1"
 rand = "0.4.2"
 wabt = "0.6"
 
+[features]
+default = ["std"]
+# Disable for no_std support
+std = [
+    "parity-wasm/std",
+    "wasmi-validation/std",
+]
+# Enable for no_std support
+# hashbrown only works on no_std
+core = [
+    "wasmi-validation/core",
+    "hashbrown/nightly",
+    "libm"
+]
+
 [workspace]
 members = ["validation"]
diff --git a/src/func.rs b/src/func.rs
index bc650dd..3f51ce9 100644
--- a/src/func.rs
+++ b/src/func.rs
@@ -1,5 +1,5 @@
 #[allow(unused_imports)]
-use alloc::prelude::*;
+use alloc::prelude::v1::*;
 use alloc::rc::{Rc, Weak};
 use core::fmt;
 use host::Externals;
diff --git a/src/imports.rs b/src/imports.rs
index 44866a7..5cd72eb 100644
--- a/src/imports.rs
+++ b/src/imports.rs
@@ -1,5 +1,5 @@
 #[allow(unused_imports)]
-use alloc::prelude::*;
+use alloc::prelude::v1::*;
 
 #[cfg(not(feature = "std"))]
 use hashbrown::HashMap;
diff --git a/src/isa.rs b/src/isa.rs
index 0325f4e..01bc69c 100644
--- a/src/isa.rs
+++ b/src/isa.rs
@@ -68,7 +68,7 @@
 //!
 
 #[allow(unused_imports)]
-use alloc::prelude::*;
+use alloc::prelude::v1::*;
 
 /// Should we keep a value before "discarding" a stack frame?
 ///
diff --git a/src/lib.rs b/src/lib.rs
index 93b7aa9..6b0604f 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -97,7 +97,7 @@
 #![warn(missing_docs)]
 #![cfg_attr(not(feature = "std"), no_std)]
 //// alloc is required in no_std
-#![cfg_attr(not(feature = "std"), feature(alloc))]
+#![cfg_attr(not(feature = "std"), feature(alloc, alloc_prelude))]
 
 #[cfg(not(feature = "std"))]
 #[macro_use]
@@ -123,7 +123,7 @@ extern crate parity_wasm;
 extern crate wasmi_validation as validation;
 
 #[allow(unused_imports)]
-use alloc::prelude::*;
+use alloc::prelude::v1::*;
 use core::fmt;
 #[cfg(feature = "std")]
 use std::error;
diff --git a/src/memory.rs b/src/memory.rs
index 9f3302f..f9ad91c 100644
--- a/src/memory.rs
+++ b/src/memory.rs
@@ -1,5 +1,5 @@
 #[allow(unused_imports)]
-use alloc::prelude::*;
+use alloc::prelude::v1::*;
 use alloc::rc::Rc;
 use core::cell::{Cell, RefCell};
 use core::cmp;
diff --git a/src/module.rs b/src/module.rs
index 51666d8..c3b30e2 100644
--- a/src/module.rs
+++ b/src/module.rs
@@ -1,5 +1,5 @@
 #[allow(unused_imports)]
-use alloc::prelude::*;
+use alloc::prelude::v1::*;
 use alloc::rc::Rc;
 use core::cell::RefCell;
 use core::fmt;
diff --git a/src/prepare/compile.rs b/src/prepare/compile.rs
index e402cc8..c72d095 100644
--- a/src/prepare/compile.rs
+++ b/src/prepare/compile.rs
@@ -1,3 +1,6 @@
+#[allow(unused_imports)]
+use alloc::prelude::v1::*;
+
 use parity_wasm::elements::{BlockType, Instruction};
 
 use validation::func::{
diff --git a/src/prepare/mod.rs b/src/prepare/mod.rs
index 790c126..e3c0eae 100644
--- a/src/prepare/mod.rs
+++ b/src/prepare/mod.rs
@@ -1,3 +1,6 @@
+#[allow(unused_imports)]
+use alloc::prelude::v1::*;
+
 use crate::{
     isa,
     validation::{validate_module2, Error, Validation},
diff --git a/src/runner.rs b/src/runner.rs
index edd23ac..9425844 100644
--- a/src/runner.rs
+++ b/src/runner.rs
@@ -1,5 +1,5 @@
 #[allow(unused_imports)]
-use alloc::prelude::*;
+use alloc::prelude::v1::*;
 use core::fmt;
 use core::ops;
 use core::{u32, usize};
diff --git a/src/table.rs b/src/table.rs
index 7d8d744..63b633f 100644
--- a/src/table.rs
+++ b/src/table.rs
@@ -1,5 +1,5 @@
 #[allow(unused_imports)]
-use alloc::prelude::*;
+use alloc::prelude::v1::*;
 use alloc::rc::Rc;
 use core::cell::RefCell;
 use core::fmt;
diff --git a/validation/Cargo.toml b/validation/Cargo.toml
index 88baefe..a5775fa 100644
--- a/validation/Cargo.toml
+++ b/validation/Cargo.toml
@@ -7,7 +7,11 @@ edition = "2018"
 [dependencies]
 parity-wasm = { version = "0.31", default-features = false }
 memory_units_crate = { package = "memory_units", version = "0.3.0" }
+hashbrown = { version = "0.1.8", optional = true }
 
 [features]
 default = ["std"]
 std = ["parity-wasm/std"]
+core = [
+    "hashbrown/nightly"
+]
diff --git a/validation/src/context.rs b/validation/src/context.rs
index f95fe70..e7de32b 100644
--- a/validation/src/context.rs
+++ b/validation/src/context.rs
@@ -1,6 +1,6 @@
 use crate::Error;
 #[allow(unused_imports)]
-use alloc::prelude::*;
+use alloc::prelude::v1::*;
 use parity_wasm::elements::{
     BlockType, FunctionType, GlobalType, MemoryType, TableType, ValueType,
 };
diff --git a/validation/src/func.rs b/validation/src/func.rs
index b7fc28d..05efd2e 100644
--- a/validation/src/func.rs
+++ b/validation/src/func.rs
@@ -1,5 +1,5 @@
 #[allow(unused_imports)]
-use alloc::prelude::*;
+use alloc::prelude::v1::*;
 
 use crate::{
     context::ModuleContext, stack::StackWithLimit, util::Locals, Error, FunctionValidator,
diff --git a/validation/src/lib.rs b/validation/src/lib.rs
index 6a0df73..f46c5a5 100644
--- a/validation/src/lib.rs
+++ b/validation/src/lib.rs
@@ -3,7 +3,7 @@
 
 #![cfg_attr(not(feature = "std"), no_std)]
 //// alloc is required in no_std
-#![cfg_attr(not(feature = "std"), feature(alloc))]
+#![cfg_attr(not(feature = "std"), feature(alloc, alloc_prelude))]
 
 #[cfg(not(feature = "std"))]
 #[macro_use]
@@ -22,7 +22,7 @@ pub const DEFAULT_TABLE_INDEX: u32 = 0;
 pub const LINEAR_MEMORY_MAX_PAGES: Pages = Pages(65536);
 
 #[allow(unused_imports)]
-use alloc::prelude::*;
+use alloc::prelude::v1::*;
 use core::fmt;
 #[cfg(feature = "std")]
 use std::error;
@@ -167,8 +167,6 @@ pub fn deny_floating_point(module: &Module) -> Result<(), Error> {
     }
 
     if let (Some(sec), Some(types)) = (module.function_section(), module.type_section()) {
-        use parity_wasm::elements::{Type, ValueType};
-
         let types = types.types();
 
         for sig in sec.entries() {
diff --git a/validation/src/stack.rs b/validation/src/stack.rs
index 9e96a63..6f1166a 100644
--- a/validation/src/stack.rs
+++ b/validation/src/stack.rs
@@ -1,5 +1,5 @@
 #[allow(unused_imports)]
-use alloc::prelude::*;
+use alloc::prelude::v1::*;
 
 use core::fmt;
 #[cfg(feature = "std")]
diff --git a/validation/src/util.rs b/validation/src/util.rs
index 44639ef..3fb6c1c 100644
--- a/validation/src/util.rs
+++ b/validation/src/util.rs
@@ -1,6 +1,6 @@
 use crate::Error;
 #[allow(unused_imports)]
-use alloc::prelude::*;
+use alloc::prelude::v1::*;
 use parity_wasm::elements::{Local, ValueType};
 
 /// Locals are the concatenation of a slice of function parameters