diff --git a/crates/lang/ir/src/ir/attrs.rs b/crates/lang/ir/src/ir/attrs.rs
index 6f50373d8f..64fa45efbb 100644
--- a/crates/lang/ir/src/ir/attrs.rs
+++ b/crates/lang/ir/src/ir/attrs.rs
@@ -766,11 +766,16 @@ impl TryFrom<syn::NestedMeta> for AttributeFrag {
                         }
                         if name_value.path.is_ident("namespace") {
                             if let syn::Lit::Str(lit_str) = &name_value.lit {
-                                let bytes = lit_str.value().into_bytes();
+                                let argument = lit_str.value();
+                                syn::parse_str::<syn::Ident>(&argument)
+                                    .map_err(|_error| format_err!(
+                                        lit_str,
+                                        "encountered invalid Rust identifier for namespace argument",
+                                    ))?;
                                 return Ok(AttributeFrag {
                                     ast: meta,
                                     arg: AttributeArg::Namespace(
-                                        Namespace::from(bytes),
+                                        Namespace::from(argument.into_bytes()),
                                     ),
                                 })
                             }
@@ -1090,6 +1095,16 @@ mod tests {
         );
     }
 
+    #[test]
+    fn namespace_invalid_identifier() {
+        assert_attribute_try_from(
+            syn::parse_quote! {
+                #[ink(namespace = "::invalid_identifier")]
+            },
+            Err("encountered invalid Rust identifier for namespace argument"),
+        );
+    }
+
     #[test]
     fn namespace_invalid_type() {
         assert_attribute_try_from(
diff --git a/crates/lang/macro/tests/compile_tests.rs b/crates/lang/macro/tests/compile_tests.rs
index 65b51b6cf4..fc0ea55aeb 100644
--- a/crates/lang/macro/tests/compile_tests.rs
+++ b/crates/lang/macro/tests/compile_tests.rs
@@ -60,5 +60,9 @@ fn compile_tests() {
     t.compile_fail("tests/ui/fail/S-05-storage-as-event.rs");
     t.compile_fail("tests/ui/fail/S-06-event-as-storage.rs");
 
+    t.compile_fail("tests/ui/fail/N-01-namespace-invalid-identifier.rs");
+    t.compile_fail("tests/ui/fail/N-02-namespace-invalid-type.rs");
+    t.compile_fail("tests/ui/fail/N-03-namespace-missing-argument.rs");
+
     t.pass("tests/ui/chain_extension/E-01-simple.rs");
 }
diff --git a/crates/lang/macro/tests/ui/fail/N-01-namespace-invalid-identifier.rs b/crates/lang/macro/tests/ui/fail/N-01-namespace-invalid-identifier.rs
new file mode 100644
index 0000000000..21d08c2d3d
--- /dev/null
+++ b/crates/lang/macro/tests/ui/fail/N-01-namespace-invalid-identifier.rs
@@ -0,0 +1,20 @@
+use ink_lang as ink;
+
+#[ink::contract]
+mod invalid_namespace_identifier {
+    #[ink(storage)]
+    pub struct MyStorage {}
+
+    #[ink(namespace = "::invalid_identifier")]
+    impl MyStorage {
+        #[ink(constructor)]
+        pub fn constructor() -> Self {
+            Self {}
+        }
+
+        #[ink(message)]
+        pub fn message(&self) {}
+    }
+}
+
+fn main() {}
diff --git a/crates/lang/macro/tests/ui/fail/N-01-namespace-invalid-identifier.stderr b/crates/lang/macro/tests/ui/fail/N-01-namespace-invalid-identifier.stderr
new file mode 100644
index 0000000000..8e3bacd08e
--- /dev/null
+++ b/crates/lang/macro/tests/ui/fail/N-01-namespace-invalid-identifier.stderr
@@ -0,0 +1,5 @@
+error: encountered invalid Rust identifier for namespace argument
+ --> $DIR/N-01-namespace-invalid-identifier.rs:8:23
+  |
+8 |     #[ink(namespace = "::invalid_identifier")]
+  |                       ^^^^^^^^^^^^^^^^^^^^^^
diff --git a/crates/lang/macro/tests/ui/fail/N-02-namespace-invalid-type.rs b/crates/lang/macro/tests/ui/fail/N-02-namespace-invalid-type.rs
new file mode 100644
index 0000000000..60871df1e5
--- /dev/null
+++ b/crates/lang/macro/tests/ui/fail/N-02-namespace-invalid-type.rs
@@ -0,0 +1,20 @@
+use ink_lang as ink;
+
+#[ink::contract]
+mod invalid_namespace_identifier {
+    #[ink(storage)]
+    pub struct MyStorage {}
+
+    #[ink(namespace = true)]
+    impl MyStorage {
+        #[ink(constructor)]
+        pub fn constructor() -> Self {
+            Self {}
+        }
+
+        #[ink(message)]
+        pub fn message(&self) {}
+    }
+}
+
+fn main() {}
diff --git a/crates/lang/macro/tests/ui/fail/N-02-namespace-invalid-type.stderr b/crates/lang/macro/tests/ui/fail/N-02-namespace-invalid-type.stderr
new file mode 100644
index 0000000000..aed0beed38
--- /dev/null
+++ b/crates/lang/macro/tests/ui/fail/N-02-namespace-invalid-type.stderr
@@ -0,0 +1,5 @@
+error: expecteded string type for `namespace` argument, e.g. #[ink(namespace = "hello")]
+ --> $DIR/N-02-namespace-invalid-type.rs:8:11
+  |
+8 |     #[ink(namespace = true)]
+  |           ^^^^^^^^^^^^^^^^
diff --git a/crates/lang/macro/tests/ui/fail/N-03-namespace-missing-argument.rs b/crates/lang/macro/tests/ui/fail/N-03-namespace-missing-argument.rs
new file mode 100644
index 0000000000..a4af79c249
--- /dev/null
+++ b/crates/lang/macro/tests/ui/fail/N-03-namespace-missing-argument.rs
@@ -0,0 +1,20 @@
+use ink_lang as ink;
+
+#[ink::contract]
+mod invalid_namespace_identifier {
+    #[ink(storage)]
+    pub struct MyStorage {}
+
+    #[ink(namespace)]
+    impl MyStorage {
+        #[ink(constructor)]
+        pub fn constructor() -> Self {
+            Self {}
+        }
+
+        #[ink(message)]
+        pub fn message(&self) {}
+    }
+}
+
+fn main() {}
diff --git a/crates/lang/macro/tests/ui/fail/N-03-namespace-missing-argument.stderr b/crates/lang/macro/tests/ui/fail/N-03-namespace-missing-argument.stderr
new file mode 100644
index 0000000000..e5298677d2
--- /dev/null
+++ b/crates/lang/macro/tests/ui/fail/N-03-namespace-missing-argument.stderr
@@ -0,0 +1,5 @@
+error: encountered #[ink(namespace)] that is missing its string parameter. Did you mean #[ink(namespace = name: str)] ?
+ --> $DIR/N-03-namespace-missing-argument.rs:8:11
+  |
+8 |     #[ink(namespace)]
+  |           ^^^^^^^^^