diff --git a/wasmtime-environ/Cargo.toml b/wasmtime-environ/Cargo.toml
index c500d961cb..e75b179db0 100644
--- a/wasmtime-environ/Cargo.toml
+++ b/wasmtime-environ/Cargo.toml
@@ -16,7 +16,6 @@ cranelift-codegen = "0.30.0"
 cranelift-entity = "0.30.0"
 cranelift-wasm = "0.30.0"
 lightbeam = { path = "../lightbeam", optional = true }
-cast = { version = "0.2.2", default-features = false }
 failure = { version = "0.1.3", default-features = false }
 failure_derive = { version = "0.1.3", default-features = false }
 indexmap = "1.0.2"
diff --git a/wasmtime-environ/src/func_environ.rs b/wasmtime-environ/src/func_environ.rs
index fbe675647f..71c8190cab 100644
--- a/wasmtime-environ/src/func_environ.rs
+++ b/wasmtime-environ/src/func_environ.rs
@@ -1,8 +1,8 @@
 use crate::module::{MemoryPlan, MemoryStyle, Module, TableStyle};
 use crate::vmoffsets::VMOffsets;
 use crate::WASM_PAGE_SIZE;
-use cast;
 use core::clone::Clone;
+use core::convert::TryFrom;
 use cranelift_codegen::cursor::FuncCursor;
 use cranelift_codegen::ir;
 use cranelift_codegen::ir::condcodes::*;
@@ -353,8 +353,8 @@ impl<'module_environment> cranelift_wasm::FuncEnvironment for FuncEnvironment<'m
             let vmctx = self.vmctx(func);
             if let Some(def_index) = self.module.defined_table_index(index) {
                 let base_offset =
-                    cast::i32(self.offsets.vmctx_vmtable_definition_base(def_index)).unwrap();
-                let current_elements_offset = cast::i32(
+                    i32::try_from(self.offsets.vmctx_vmtable_definition_base(def_index)).unwrap();
+                let current_elements_offset = i32::try_from(
                     self.offsets
                         .vmctx_vmtable_definition_current_elements(def_index),
                 )
@@ -364,7 +364,7 @@ impl<'module_environment> cranelift_wasm::FuncEnvironment for FuncEnvironment<'m
                 let from_offset = self.offsets.vmctx_vmtable_import_from(index);
                 let table = func.create_global_value(ir::GlobalValueData::Load {
                     base: vmctx,
-                    offset: Offset32::new(cast::i32(from_offset).unwrap()),
+                    offset: Offset32::new(i32::try_from(from_offset).unwrap()),
                     global_type: pointer_type,
                     readonly: true,
                 });
@@ -410,8 +410,8 @@ impl<'module_environment> cranelift_wasm::FuncEnvironment for FuncEnvironment<'m
             let vmctx = self.vmctx(func);
             if let Some(def_index) = self.module.defined_memory_index(index) {
                 let base_offset =
-                    cast::i32(self.offsets.vmctx_vmmemory_definition_base(def_index)).unwrap();
-                let current_length_offset = cast::i32(
+                    i32::try_from(self.offsets.vmctx_vmmemory_definition_base(def_index)).unwrap();
+                let current_length_offset = i32::try_from(
                     self.offsets
                         .vmctx_vmmemory_definition_current_length(def_index),
                 )
@@ -421,7 +421,7 @@ impl<'module_environment> cranelift_wasm::FuncEnvironment for FuncEnvironment<'m
                 let from_offset = self.offsets.vmctx_vmmemory_import_from(index);
                 let memory = func.create_global_value(ir::GlobalValueData::Load {
                     base: vmctx,
-                    offset: Offset32::new(cast::i32(from_offset).unwrap()),
+                    offset: Offset32::new(i32::try_from(from_offset).unwrap()),
                     global_type: pointer_type,
                     readonly: true,
                 });
@@ -488,13 +488,14 @@ impl<'module_environment> cranelift_wasm::FuncEnvironment for FuncEnvironment<'m
         let (ptr, offset) = {
             let vmctx = self.vmctx(func);
             if let Some(def_index) = self.module.defined_global_index(index) {
-                let offset = cast::i32(self.offsets.vmctx_vmglobal_definition(def_index)).unwrap();
+                let offset =
+                    i32::try_from(self.offsets.vmctx_vmglobal_definition(def_index)).unwrap();
                 (vmctx, offset)
             } else {
                 let from_offset = self.offsets.vmctx_vmglobal_import_from(index);
                 let global = func.create_global_value(ir::GlobalValueData::Load {
                     base: vmctx,
-                    offset: Offset32::new(cast::i32(from_offset).unwrap()),
+                    offset: Offset32::new(i32::try_from(from_offset).unwrap()),
                     global_type: pointer_type,
                     readonly: true,
                 });
@@ -548,7 +549,7 @@ impl<'module_environment> cranelift_wasm::FuncEnvironment for FuncEnvironment<'m
                 let vmctx = self.vmctx(pos.func);
                 let base = pos.ins().global_value(pointer_type, vmctx);
                 let offset =
-                    cast::i32(self.offsets.vmctx_vmshared_signature_id(sig_index)).unwrap();
+                    i32::try_from(self.offsets.vmctx_vmshared_signature_id(sig_index)).unwrap();
 
                 // Load the caller ID.
                 let mut mem_flags = ir::MemFlags::trusted();
@@ -627,12 +628,12 @@ impl<'module_environment> cranelift_wasm::FuncEnvironment for FuncEnvironment<'m
 
         // Load the callee address.
         let body_offset =
-            cast::i32(self.offsets.vmctx_vmfunction_import_body(callee_index)).unwrap();
+            i32::try_from(self.offsets.vmctx_vmfunction_import_body(callee_index)).unwrap();
         let func_addr = pos.ins().load(pointer_type, mem_flags, base, body_offset);
 
         // First append the callee vmctx address.
         let vmctx_offset =
-            cast::i32(self.offsets.vmctx_vmfunction_import_vmctx(callee_index)).unwrap();
+            i32::try_from(self.offsets.vmctx_vmfunction_import_vmctx(callee_index)).unwrap();
         let vmctx = pos.ins().load(pointer_type, mem_flags, base, vmctx_offset);
         real_call_args.push(vmctx);
 
diff --git a/wasmtime-environ/src/module_environ.rs b/wasmtime-environ/src/module_environ.rs
index 1fa666030e..405034763d 100644
--- a/wasmtime-environ/src/module_environ.rs
+++ b/wasmtime-environ/src/module_environ.rs
@@ -1,6 +1,7 @@
 use crate::func_environ::FuncEnvironment;
 use crate::module::{Export, MemoryPlan, Module, TableElements, TablePlan};
 use crate::tunables::Tunables;
+use core::convert::TryFrom;
 use cranelift_codegen::ir;
 use cranelift_codegen::ir::{AbiParam, ArgumentPurpose};
 use cranelift_codegen::isa::TargetFrontendConfig;
@@ -93,7 +94,7 @@ impl<'data> cranelift_wasm::ModuleEnvironment<'data> for ModuleEnvironment<'data
         self.result
             .module
             .signatures
-            .reserve_exact(cast::usize(num));
+            .reserve_exact(usize::try_from(num).unwrap());
     }
 
     fn declare_signature(&mut self, sig: ir::Signature) {
@@ -168,10 +169,13 @@ impl<'data> cranelift_wasm::ModuleEnvironment<'data> for ModuleEnvironment<'data
     }
 
     fn reserve_func_types(&mut self, num: u32) {
-        self.result.module.functions.reserve_exact(cast::usize(num));
+        self.result
+            .module
+            .functions
+            .reserve_exact(usize::try_from(num).unwrap());
         self.result
             .function_body_inputs
-            .reserve_exact(cast::usize(num));
+            .reserve_exact(usize::try_from(num).unwrap());
     }
 
     fn declare_func_type(&mut self, sig_index: SignatureIndex) {
@@ -182,7 +186,7 @@ impl<'data> cranelift_wasm::ModuleEnvironment<'data> for ModuleEnvironment<'data
         self.result
             .module
             .table_plans
-            .reserve_exact(cast::usize(num));
+            .reserve_exact(usize::try_from(num).unwrap());
     }
 
     fn declare_table(&mut self, table: Table) {
@@ -194,7 +198,7 @@ impl<'data> cranelift_wasm::ModuleEnvironment<'data> for ModuleEnvironment<'data
         self.result
             .module
             .memory_plans
-            .reserve_exact(cast::usize(num));
+            .reserve_exact(usize::try_from(num).unwrap());
     }
 
     fn declare_memory(&mut self, memory: Memory) {
@@ -203,7 +207,10 @@ impl<'data> cranelift_wasm::ModuleEnvironment<'data> for ModuleEnvironment<'data
     }
 
     fn reserve_globals(&mut self, num: u32) {
-        self.result.module.globals.reserve_exact(cast::usize(num));
+        self.result
+            .module
+            .globals
+            .reserve_exact(usize::try_from(num).unwrap());
     }
 
     fn declare_global(&mut self, global: Global) {
@@ -211,7 +218,10 @@ impl<'data> cranelift_wasm::ModuleEnvironment<'data> for ModuleEnvironment<'data
     }
 
     fn reserve_exports(&mut self, num: u32) {
-        self.result.module.exports.reserve(cast::usize(num));
+        self.result
+            .module
+            .exports
+            .reserve(usize::try_from(num).unwrap());
     }
 
     fn declare_func_export(&mut self, func_index: FuncIndex, name: &str) {
@@ -251,7 +261,7 @@ impl<'data> cranelift_wasm::ModuleEnvironment<'data> for ModuleEnvironment<'data
         self.result
             .module
             .table_elements
-            .reserve_exact(cast::usize(num));
+            .reserve_exact(usize::try_from(num).unwrap());
     }
 
     fn declare_table_elements(
@@ -284,7 +294,7 @@ impl<'data> cranelift_wasm::ModuleEnvironment<'data> for ModuleEnvironment<'data
     fn reserve_data_initializers(&mut self, num: u32) {
         self.result
             .data_initializers
-            .reserve_exact(cast::usize(num));
+            .reserve_exact(usize::try_from(num).unwrap());
     }
 
     fn declare_data_initialization(
diff --git a/wasmtime-environ/src/vmoffsets.rs b/wasmtime-environ/src/vmoffsets.rs
index a54fb3dc98..ae7a0ea4e1 100644
--- a/wasmtime-environ/src/vmoffsets.rs
+++ b/wasmtime-environ/src/vmoffsets.rs
@@ -2,7 +2,7 @@
 //! module.
 
 use crate::module::Module;
-use cast;
+use core::convert::TryFrom;
 use cranelift_codegen::ir;
 use cranelift_wasm::{
     DefinedGlobalIndex, DefinedMemoryIndex, DefinedTableIndex, FuncIndex, GlobalIndex, MemoryIndex,
@@ -11,11 +11,11 @@ use cranelift_wasm::{
 
 #[cfg(target_pointer_width = "32")]
 fn cast_to_u32(sz: usize) -> u32 {
-    cast::u32(sz)
+    u32::try_from(sz).unwrap()
 }
 #[cfg(target_pointer_width = "64")]
 fn cast_to_u32(sz: usize) -> u32 {
-    match cast::u32(sz) {
+    match u32::try_from(sz) {
         Ok(x) => x,
         Err(_) => panic!("overflow in cast from usize to u32"),
     }