diff --git a/src/ensure.rs b/src/ensure.rs
index e442597..d52fd52 100644
--- a/src/ensure.rs
+++ b/src/ensure.rs
@@ -365,6 +365,18 @@ macro_rules! __parse_ensure {
         $crate::__parse_ensure!(type $stack $bail ($($fuel)*) {($($buf)* $and) $($parse)*} ($($rest)*) $($rest)*)
     };
 
+    (type $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($unsafe:tt $(extern $($abi:literal)?)? fn $($dup:tt)*) unsafe $($rest:tt)*) => {
+        $crate::__parse_ensure!(type $stack $bail ($($fuel)*) {($($buf)* $unsafe) $($parse)*} ($($rest)*) $($rest)*)
+    };
+
+    (type $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($extern:tt $abi:literal fn $($dup:tt)*) extern $lit:literal $($rest:tt)*) => {
+        $crate::__parse_ensure!(type $stack $bail ($($fuel)*) {($($buf)* $extern $abi) $($parse)*} ($($rest)*) $($rest)*)
+    };
+
+    (type $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($extern:tt fn $($dup:tt)*) extern $($rest:tt)*) => {
+        $crate::__parse_ensure!(type $stack $bail ($($fuel)*) {($($buf)* $extern) $($parse)*} ($($rest)*) $($rest)*)
+    };
+
     (type $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($fn:tt $paren:tt $arrow:tt $($dup:tt)*) fn ($($args:tt)*) -> $($rest:tt)*) => {
         $crate::__parse_ensure!(type $stack $bail ($($fuel)*) {($($buf)* $fn $paren $arrow) $($parse)*} ($($rest)*) $($rest)*)
     };
diff --git a/tests/test_ensure.rs b/tests/test_ensure.rs
index a0d6f6f..62c1ac9 100644
--- a/tests/test_ensure.rs
+++ b/tests/test_ensure.rs
@@ -9,6 +9,7 @@
     clippy::never_loop,
     clippy::redundant_closure_call,
     clippy::redundant_pattern_matching,
+    clippy::too_many_lines,
     clippy::unit_arg,
     clippy::while_immutable_condition,
     clippy::zero_ptr
@@ -507,6 +508,27 @@ fn test_as() {
         "Condition failed: `f as for<'a>fn() as usize * 0 != 0` (0 vs 0)",
     );
 
+    let test = || Ok(ensure!(f as unsafe fn() as usize * 0 != 0));
+    assert_err(
+        test,
+        "Condition failed: `f as unsafe fn() as usize * 0 != 0` (0 vs 0)",
+    );
+
+    #[rustfmt::skip]
+    let test = || Ok(ensure!(f as extern "Rust" fn() as usize * 0 != 0));
+    assert_err(
+        test,
+        "Condition failed: `f as extern \"Rust\" fn() as usize * 0 != 0` (0 vs 0)",
+    );
+
+    extern "C" fn extern_fn() {}
+    #[rustfmt::skip]
+    let test = || Ok(ensure!(extern_fn as extern fn() as usize * 0 != 0));
+    assert_err(
+        test,
+        "Condition failed: `extern_fn as extern fn() as usize * 0 != 0` (0 vs 0)",
+    );
+
     let f = || -> ! { panic!() };
     let test = || Ok(ensure!(f as fn() -> ! as usize * 0 != 0));
     assert_err(