diff --git a/releasenotes.md b/releasenotes.md
index 6b695ac9d..b1f8f082d 100644
--- a/releasenotes.md
+++ b/releasenotes.md
@@ -28,6 +28,7 @@
 - Struct members declared in a single line declaration were not sharing attributes. #1266
 - `opt` project setting now properly documented.
 - Incorrect justify formatting of integers.
+- Assertion with duplicate function pointer signatures #1286
 
 ### Stdlib changes
 
diff --git a/src/compiler/codegen_internal.h b/src/compiler/codegen_internal.h
index cd860f8e2..3694d3eef 100644
--- a/src/compiler/codegen_internal.h
+++ b/src/compiler/codegen_internal.h
@@ -36,6 +36,11 @@ static inline Type *type_lowering(Type *type)
 			case TYPE_ENUM:
 				type = type->decl->enums.type_info->type;
 				continue;
+			case TYPE_FUNC_PTR:
+				if (type->pointer->function.prototype->raw_type == type->pointer) return type;
+				return type_get_func_ptr(type->pointer->function.prototype->raw_type);
+			case TYPE_FUNC_RAW:
+				return type->function.prototype->raw_type;
 			case TYPE_INTERFACE:
 				return type_any;
 			case TYPE_ANYFAULT:
diff --git a/test/test_suite/functions/function_alias_llvm_check.c3t b/test/test_suite/functions/function_alias_llvm_check.c3t
new file mode 100644
index 000000000..7214c2e14
--- /dev/null
+++ b/test/test_suite/functions/function_alias_llvm_check.c3t
@@ -0,0 +1,50 @@
+// #target: macos-x64
+module repro;
+
+import std::collections::list;
+
+def FnA = fn void(Foo*);
+def FnB = fn void(Foo*);
+
+struct Foo
+{
+    List(<FnA>) aFuncs;
+    List(<FnB>) bFuncs;
+}
+
+fn void! Foo.deinit(&self)
+{
+    self.aFuncs.free();
+    self.bFuncs.free();
+}
+
+fn void Foo.add_fn_a(&self, FnA f) => self.aFuncs.push(f);
+fn void Foo.add_fn_b(&self, FnB f) => self.bFuncs.push(f);
+
+fn void a_func(Foo* foo) {}
+fn void b_func(Foo* foo) {}
+
+fn void! main()
+{
+    Foo foo;
+    defer foo.deinit()!!;
+    foo.add_fn_a(&a_func);
+    foo.add_fn_b(&b_func);
+}
+
+/* #expect: repro.ll
+
+define i64 @repro.main() #0 {
+entry:
+  %foo = alloca %Foo, align 8
+  %error_var = alloca i64, align 8
+  %varargslots = alloca [1 x %any], align 16
+  %indirectarg = alloca %"any[]", align 8
+  call void @llvm.memset.p0.i64(ptr align 8 %foo, i8 0, i64 80, i1 false)
+  call void @repro.Foo.add_fn_a(ptr %foo, ptr @repro.a_func)
+  call void @repro.Foo.add_fn_b(ptr %foo, ptr @repro.b_func)
+  %0 = call i64 @repro.Foo.deinit(ptr %foo)
+  %not_err = icmp eq i64 %0, 0
+  %1 = call i1 @llvm.expect.i1(i1 %not_err, i1 true)
+  br i1 %1, label %after_check, label %assign_optional
+