diff --git a/lib/runtime-core/src/backing.rs b/lib/runtime-core/src/backing.rs
index d413ef00e..f9b320b45 100644
--- a/lib/runtime-core/src/backing.rs
+++ b/lib/runtime-core/src/backing.rs
@@ -15,7 +15,11 @@ use crate::{
     },
     vm,
 };
-use std::{fmt::Debug, ptr, slice};
+use std::{
+    fmt::Debug,
+    ptr::{self, NonNull},
+    slice,
+};
 
 pub const INTERNALS_SIZE: usize = 256;
 
@@ -382,9 +386,9 @@ impl LocalBacking {
                                     vmctx,
                                 ),
                                 LocalOrImport::Import(imported_func_index) => {
-                                    let vm::ImportedFunc { func, vmctx } =
+                                    let vm::ImportedFunc { func, func_ctx } =
                                         imports.vm_functions[imported_func_index];
-                                    (func, vmctx as _)
+                                    (func, unsafe { func_ctx.as_ref() }.vmctx.as_ptr())
                                 }
                             };
 
@@ -415,9 +419,9 @@ impl LocalBacking {
                                     vmctx,
                                 ),
                                 LocalOrImport::Import(imported_func_index) => {
-                                    let vm::ImportedFunc { func, vmctx } =
+                                    let vm::ImportedFunc { func, func_ctx } =
                                         imports.vm_functions[imported_func_index];
-                                    (func, vmctx as _)
+                                    (func, unsafe { func_ctx.as_ref() }.vmctx.as_ptr())
                                 }
                             };
 
@@ -544,8 +548,7 @@ impl ImportBacking {
 impl Drop for ImportBacking {
     fn drop(&mut self) {
         for (_imported_func_index, imported_func) in (*self.vm_functions).iter_mut() {
-            let _: Box<vm::FuncCtx> = unsafe { Box::from_raw(imported_func.vmctx) };
-            imported_func.vmctx = ptr::null_mut();
+            let _: Box<vm::FuncCtx> = unsafe { Box::from_raw(imported_func.func_ctx.as_ptr()) };
         }
     }
 }
@@ -583,16 +586,17 @@ fn import_functions(
                 if *expected_sig == *signature {
                     functions.push(vm::ImportedFunc {
                         func: func.inner(),
-                        vmctx: {
+                        func_ctx: {
                             let _ = match ctx {
                                 Context::External(ctx) => ctx,
                                 Context::Internal => vmctx,
                             };
 
-                            Box::into_raw(Box::new(vm::FuncCtx {
-                                vmctx,
+                            NonNull::new(Box::into_raw(Box::new(vm::FuncCtx {
+                                vmctx: NonNull::new(vmctx).expect("`vmctx` must not be null."),
                                 func_env: ptr::null_mut(),
-                            }))
+                            })))
+                            .unwrap()
                         },
                     });
                 } else {
@@ -622,8 +626,8 @@ fn import_functions(
             None => {
                 if imports.allow_missing_functions {
                     functions.push(vm::ImportedFunc {
-                        func: ::std::ptr::null(),
-                        vmctx: ::std::ptr::null_mut(),
+                        func: ptr::null(),
+                        func_ctx: unsafe { NonNull::new_unchecked(ptr::null_mut()) }, // TODO: Non-sense…
                     });
                 } else {
                     link_errors.push(LinkError::ImportNotFound {
diff --git a/lib/runtime-core/src/instance.rs b/lib/runtime-core/src/instance.rs
index 2716e272a..5cf92a312 100644
--- a/lib/runtime-core/src/instance.rs
+++ b/lib/runtime-core/src/instance.rs
@@ -110,9 +110,13 @@ impl Instance {
 
             let ctx_ptr = match start_index.local_or_import(&instance.module.info) {
                 LocalOrImport::Local(_) => instance.inner.vmctx,
-                LocalOrImport::Import(imported_func_index) => {
-                    instance.inner.import_backing.vm_functions[imported_func_index].vmctx as _
+                LocalOrImport::Import(imported_func_index) => unsafe {
+                    instance.inner.import_backing.vm_functions[imported_func_index]
+                        .func_ctx
+                        .as_ref()
                 }
+                .vmctx
+                .as_ptr(),
             };
 
             let sig_index = *instance
@@ -195,9 +199,13 @@ impl Instance {
 
             let ctx = match func_index.local_or_import(&self.module.info) {
                 LocalOrImport::Local(_) => self.inner.vmctx,
-                LocalOrImport::Import(imported_func_index) => {
-                    self.inner.import_backing.vm_functions[imported_func_index].vmctx as _
+                LocalOrImport::Import(imported_func_index) => unsafe {
+                    self.inner.import_backing.vm_functions[imported_func_index]
+                        .func_ctx
+                        .as_ref()
                 }
+                .vmctx
+                .as_ptr(),
             };
 
             let func_wasm_inner = self
@@ -449,7 +457,7 @@ impl InstanceInner {
                 let imported_func = &self.import_backing.vm_functions[imported_func_index];
                 (
                     imported_func.func as *const _,
-                    Context::External(imported_func.vmctx as _),
+                    Context::External(unsafe { imported_func.func_ctx.as_ref() }.vmctx.as_ptr()),
                 )
             }
         };
@@ -574,9 +582,13 @@ fn call_func_with_index(
 
     let ctx_ptr = match func_index.local_or_import(info) {
         LocalOrImport::Local(_) => local_ctx,
-        LocalOrImport::Import(imported_func_index) => {
-            import_backing.vm_functions[imported_func_index].vmctx as _
+        LocalOrImport::Import(imported_func_index) => unsafe {
+            import_backing.vm_functions[imported_func_index]
+                .func_ctx
+                .as_ref()
         }
+        .vmctx
+        .as_ptr(),
     };
 
     let wasm = runnable
diff --git a/lib/runtime-core/src/typed_func.rs b/lib/runtime-core/src/typed_func.rs
index 8e0819985..049dfc161 100644
--- a/lib/runtime-core/src/typed_func.rs
+++ b/lib/runtime-core/src/typed_func.rs
@@ -498,7 +498,7 @@ macro_rules! impl_traits {
                         Trap: TrapEarly<Rets>,
                         FN: Fn(&mut vm::Ctx, $( $x, )*) -> Trap,
                     {
-                        let vmctx = unsafe { &mut *func_ctx.vmctx };
+                        let vmctx = unsafe { func_ctx.vmctx.as_mut() };
                         let f: FN = unsafe { mem::transmute_copy(&()) };
 
                         let err = match panic::catch_unwind(
@@ -557,7 +557,7 @@ macro_rules! impl_traits {
                         Trap: TrapEarly<Rets>,
                         FN: Fn($( $x, )*) -> Trap,
                     {
-                        let vmctx = unsafe { &mut *func_ctx.vmctx };
+                        let vmctx = unsafe { func_ctx.vmctx.as_mut() };
                         let f: FN = unsafe { mem::transmute_copy(&()) };
 
                         let err = match panic::catch_unwind(
diff --git a/lib/runtime-core/src/vm.rs b/lib/runtime-core/src/vm.rs
index adc33f2c5..fa4d3020b 100644
--- a/lib/runtime-core/src/vm.rs
+++ b/lib/runtime-core/src/vm.rs
@@ -512,7 +512,7 @@ pub struct FuncEnv {
 #[derive(Debug)]
 #[repr(C)]
 pub struct FuncCtx {
-    pub vmctx: *mut Ctx,
+    pub vmctx: NonNull<Ctx>,
     pub func_env: *mut FuncEnv,
 }
 
@@ -521,7 +521,7 @@ pub struct FuncCtx {
 #[repr(C)]
 pub struct ImportedFunc {
     pub func: *const Func,
-    pub vmctx: *mut FuncCtx,
+    pub func_ctx: NonNull<FuncCtx>,
 }
 
 // manually implemented because ImportedFunc contains raw pointers directly; `Func` is marked Send (But `Ctx` actually isn't! (TODO: review this, shouldn't `Ctx` be Send?))