diff --git a/artiq/firmware/ksupport/api.rs b/artiq/firmware/ksupport/api.rs
index 1682f818b..7b1fa4ec2 100644
--- a/artiq/firmware/ksupport/api.rs
+++ b/artiq/firmware/ksupport/api.rs
@@ -167,4 +167,11 @@ static mut API: &'static [(&'static str, *const ())] = &[
     api!(spi_set_config = ::nrt_bus::spi::set_config),
     api!(spi_write = ::nrt_bus::spi::write),
     api!(spi_read = ::nrt_bus::spi::read),
+
+    /*
+     * syscall for unit tests
+     * Used in `artiq.tests.coredevice.test_exceptions.ExceptionTest.test_raise_exceptions_kernel`
+     * `EmbeddingMap` (`artiq.compiler.embedding`) and `EXCEPTION_ID_LOOKUP` (`artiq.firmware.ksupport.eh_artiq`)
+     */
+    api!(test_exception_id_sync = ::eh_artiq::test_exception_id_sync)
 ];
diff --git a/artiq/firmware/ksupport/eh_artiq.rs b/artiq/firmware/ksupport/eh_artiq.rs
index 66c78d23d..44dda1015 100644
--- a/artiq/firmware/ksupport/eh_artiq.rs
+++ b/artiq/firmware/ksupport/eh_artiq.rs
@@ -333,7 +333,7 @@ extern fn stop_fn(_version: c_int,
     }
 }
 
-// Must be kept in sync with `artq.compiler.embedding`
+// Must be kept in sync with `artiq.compiler.embedding`
 static EXCEPTION_ID_LOOKUP: [(&str, u32); 19] = [
     ("RTIOUnderflow", 0),
     ("RTIOOverflow", 1),
@@ -365,3 +365,25 @@ pub fn get_exception_id(name: &str) -> u32 {
     unimplemented!("unallocated internal exception id")
 }
 
+// Performs a reverse lookup on `EXCEPTION_ID_LOOKUP` 
+// Unconditionally raises an exception given its id
+#[no_mangle]
+#[unwind(allowed)]
+pub extern fn test_exception_id_sync(exn_id: u32) {
+    let message = EXCEPTION_ID_LOOKUP
+        .iter()
+        .find_map(|&(name, id)| if id == exn_id { Some(name) } else { None })
+        .unwrap_or("Unknown exception ID");
+    
+    let exn = Exception {
+        id:       exn_id,
+        file:     file!().as_c_slice(),
+        line:     0,
+        column:   0,
+        function: "test_exception_id_sync".as_c_slice(),
+        message:  message.as_c_slice(),
+        param:    [0, 0, 0]
+    };
+    unsafe { raise(&exn) };
+}
+