diff --git a/substrate/primitives/api/proc-macro/src/impl_runtime_apis.rs b/substrate/primitives/api/proc-macro/src/impl_runtime_apis.rs
index 32d4683f3dd5..8a582e171fb7 100644
--- a/substrate/primitives/api/proc-macro/src/impl_runtime_apis.rs
+++ b/substrate/primitives/api/proc-macro/src/impl_runtime_apis.rs
@@ -867,27 +867,38 @@ fn impl_runtime_apis_impl_inner(
 	let runtime_api_versions = generate_runtime_api_versions(api_impls)?;
 	let wasm_interface = generate_wasm_interface(api_impls)?;
 	let api_impls_for_runtime_api = generate_api_impl_for_runtime_api(api_impls)?;
-	let modules: Vec<TypePath> = uses
+	let modules = match uses
 		.iter()
 		.map(|item| {
 			let mut path: Vec<Ident> = vec![];
-			fn call(path: &mut Vec<Ident>, item: &UseTree) {
+			fn call(path: &mut Vec<Ident>, item: &UseTree) -> Result<()> {
 				match &item {
 					syn::UseTree::Path(use_path) => {
 						path.push(use_path.ident.clone());
-						call(path, use_path.tree.as_ref());
+						call(path, use_path.tree.as_ref())
+					},
+					syn::UseTree::Glob(_) => Ok(()),
+					syn::UseTree::Name(_) | syn::UseTree::Rename(_) | syn::UseTree::Group(_) => {
+						let error = Error::new(
+							item.span(),
+							"Unsupported syntax used to import api implementaions from an extension module. \
+							Try using `pub use <path>::*` or `use <path>::*`",
+						);
+						return Err(error)
 					},
-					syn::UseTree::Glob(_) => (),
-					syn::UseTree::Name(_) | syn::UseTree::Rename(_) | syn::UseTree::Group(_) =>
-						unimplemented!(),
 				}
 			}
-			call(&mut path, &item.tree);
+			call(&mut path, &item.tree)?;
 			let tok = quote::quote! {#(#path)::*};
-			syn::parse::<TypePath>(tok.into()).unwrap()
+			Ok(syn::parse::<TypePath>(tok.into())
+				.expect("Can't happen, a valid TypePath was used in the `UseTree`"))
 		})
-		.collect();
-
+		.collect::<Result<Vec<TypePath>>>()
+		.map_err(|e| e.into_compile_error())
+	{
+		Ok(items) => items,
+		Err(e) => return Ok(e),
+	};
 	let dispatch_impl = generate_dispatch_function(api_impls, Kind::Main(&modules))?;
 
 	let runtime_metadata =
@@ -1039,7 +1050,7 @@ mod tests {
 		};
 
 		// Parse the items
-		let RuntimeApiImpls { impls: mut api_impls, uses : _ } =
+		let RuntimeApiImpls { impls: mut api_impls, uses: _ } =
 			syn::parse2::<RuntimeApiImpls>(code).unwrap();
 
 		// Run the renamer which is being run first in the `impl_runtime_apis!` macro.
diff --git a/substrate/primitives/api/test/tests/ui/incorrect_extension_import.rs b/substrate/primitives/api/test/tests/ui/incorrect_extension_import.rs
new file mode 100644
index 000000000000..96cbf1206171
--- /dev/null
+++ b/substrate/primitives/api/test/tests/ui/incorrect_extension_import.rs
@@ -0,0 +1,61 @@
+// This file is part of Substrate.
+
+// Copyright (C) Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: Apache-2.0
+
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 	http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use sp_runtime::traits::Block as BlockT;
+use substrate_test_runtime_client::runtime::Block;
+
+struct Runtime {}
+
+sp_api::decl_runtime_apis! {
+	#[api_version(2)]
+	pub trait Api {
+		fn test1();
+		fn test2();
+		#[api_version(3)]
+		fn test3();
+		#[api_version(4)]
+		fn test4();
+	}
+}
+
+sp_api::impl_runtime_apis! {
+	impl sp_api::Core<Block> for Runtime {
+		fn version() -> sp_version::RuntimeVersion {
+			unimplemented!()
+		}
+		fn execute_block(_: Block) {
+			unimplemented!()
+		}
+		fn initialize_block(_: &<Block as BlockT>::Header) -> sp_runtime::ExtrinsicInclusionMode {
+			unimplemented!()
+		}
+	}
+
+	use example::{api, *};
+}
+
+#[sp_api::impl_runtime_apis_ext]
+mod example {
+	use super::*;
+	#[api_version(2)]
+	impl self::Api<Block> for Runtime {
+		fn test1() {}
+		fn test2() {}
+	}
+}
+
+fn main() {}
diff --git a/substrate/primitives/api/test/tests/ui/incorrect_extension_import.stderr b/substrate/primitives/api/test/tests/ui/incorrect_extension_import.stderr
new file mode 100644
index 000000000000..8eaa6dbc0456
--- /dev/null
+++ b/substrate/primitives/api/test/tests/ui/incorrect_extension_import.stderr
@@ -0,0 +1,21 @@
+error: Unsupported syntax used to import api implementaions from an extension module. Try using `pub use <path>::*` or `use <path>::*`
+  --> tests/ui/incorrect_extension_import.rs:48:15
+   |
+48 |     use example::{api, *};
+   |                  ^^^^^^^^
+
+error[E0412]: cannot find type `RuntimeApiImpl` in this scope
+  --> tests/ui/incorrect_extension_import.rs:51:1
+   |
+51 | #[sp_api::impl_runtime_apis_ext]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ not found in this scope
+   |
+   = note: this error originates in the attribute macro `sp_api::impl_runtime_apis_ext` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+warning: unused import: `sp_runtime::traits::Block`
+  --> tests/ui/incorrect_extension_import.rs:18:5
+   |
+18 | use sp_runtime::traits::Block as BlockT;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `#[warn(unused_imports)]` on by default