diff --git a/src/clang.rs b/src/clang.rs
index 96f772540b..db6467e398 100644
--- a/src/clang.rs
+++ b/src/clang.rs
@@ -241,7 +241,7 @@ impl Cursor {
         self.x.kind
     }
 
-    /// Returns true is the cursor is a definition
+    /// Returns true if the cursor is a definition
     pub fn is_definition(&self) -> bool {
         unsafe { clang_isCursorDefinition(self.x) != 0 }
     }
diff --git a/src/ir/comp.rs b/src/ir/comp.rs
index 52dcddd555..d57c272a30 100644
--- a/src/ir/comp.rs
+++ b/src/ir/comp.rs
@@ -1249,6 +1249,7 @@ impl CompInfo {
         let mut ci = CompInfo::new(kind);
         ci.is_forward_declaration =
             location.map_or(true, |cur| match cur.kind() {
+                CXCursor_ParmDecl => true,
                 CXCursor_StructDecl | CXCursor_UnionDecl |
                 CXCursor_ClassDecl => !cur.is_definition(),
                 _ => false,
diff --git a/tests/expectations/tests/parm-union.rs b/tests/expectations/tests/parm-union.rs
new file mode 100644
index 0000000000..9f7dd20ad9
--- /dev/null
+++ b/tests/expectations/tests/parm-union.rs
@@ -0,0 +1,40 @@
+#![allow(
+    dead_code,
+    non_snake_case,
+    non_camel_case_types,
+    non_upper_case_globals
+)]
+
+#[repr(C)]
+#[derive(Debug, Default, Copy, Clone)]
+pub struct Struct {
+    pub _address: u8,
+}
+#[test]
+fn bindgen_test_layout_Struct() {
+    assert_eq!(
+        ::std::mem::size_of::<Struct>(),
+        1usize,
+        concat!("Size of: ", stringify!(Struct))
+    );
+    assert_eq!(
+        ::std::mem::align_of::<Struct>(),
+        1usize,
+        concat!("Alignment of ", stringify!(Struct))
+    );
+}
+extern "C" {
+    #[link_name = "\u{1}_ZN6Struct8FunctionER5Union"]
+    pub fn Struct_Function(this: *mut Struct, arg1: *mut Union);
+}
+impl Struct {
+    #[inline]
+    pub unsafe fn Function(&mut self, arg1: *mut Union) {
+        Struct_Function(self, arg1)
+    }
+}
+#[repr(C)]
+#[derive(Copy, Clone)]
+pub struct Union {
+    _unused: [u8; 0],
+}
diff --git a/tests/headers/parm-union.hpp b/tests/headers/parm-union.hpp
new file mode 100644
index 0000000000..e36df69120
--- /dev/null
+++ b/tests/headers/parm-union.hpp
@@ -0,0 +1,4 @@
+struct Struct
+{
+    void Function(union Union&);
+};