diff --git a/artiq/devices/corecom_serial.py b/artiq/devices/corecom_serial.py
index 9b0d349af..7fef4a461 100644
--- a/artiq/devices/corecom_serial.py
+++ b/artiq/devices/corecom_serial.py
@@ -6,7 +6,9 @@ from enum import Enum
 import logging
 
 from artiq.language import units
+from artiq.language import core as core_language
 from artiq.devices.runtime import Environment
+from artiq.devices import runtime_exceptions
 
 
 logger = logging.getLogger(__name__)
@@ -142,7 +144,7 @@ class CoreCom:
             _write_exactly(self.port, struct.pack("B", ord(c)))
         logger.debug("running kernel: {}".format(kname))
 
-    def serve(self, rpc_map, exception_map):
+    def serve(self, rpc_map, user_exception_map):
         while True:
             msg = self._get_device_msg()
             if msg == _D2HMsgType.RPC_REQUEST:
@@ -160,9 +162,12 @@ class CoreCom:
                 logger.debug("rpc service: {} ({}) == {}".format(
                     rpc_num, args, r))
             elif msg == _D2HMsgType.KERNEL_EXCEPTION:
-                (exception_num, ) = struct.unpack(">l",
-                                                  _read_exactly(self.port, 4))
-                raise exception_map[exception_num]
+                (eid, ) = struct.unpack(">l", _read_exactly(self.port, 4))
+                if eid < core_language.first_user_eid:
+                    exception = runtime_exceptions.exception_map[eid]
+                else:
+                    exception = user_exception_map[eid]
+                raise exception
             elif msg == _D2HMsgType.KERNEL_FINISHED:
                 return
             else:
diff --git a/artiq/devices/runtime_exceptions.py b/artiq/devices/runtime_exceptions.py
new file mode 100644
index 000000000..d01ef5bbf
--- /dev/null
+++ b/artiq/devices/runtime_exceptions.py
@@ -0,0 +1,15 @@
+class RuntimeException(Exception):
+    pass
+
+
+class OutOfMemory(RuntimeException):
+    eid = 0
+
+
+class RTIOUnderflow(RuntimeException):
+    eid = 1
+
+
+exception_map = {e.eid: e for e in globals().values()
+                 if isinstance(e, RuntimeException.__class__)
+                 and hasattr(e, "eid")}
diff --git a/artiq/language/core.py b/artiq/language/core.py
index 75da83f16..e607521a3 100644
--- a/artiq/language/core.py
+++ b/artiq/language/core.py
@@ -330,6 +330,8 @@ def syscall(*args):
 
 _encoded_exceptions = dict()
 
+first_user_eid = 1024
+
 
 def EncodedException(eid):
     """Represents exceptions on the core device, which are identified
diff --git a/artiq/transforms/inline.py b/artiq/transforms/inline.py
index 1f3a63d9c..1cb1cac08 100644
--- a/artiq/transforms/inline.py
+++ b/artiq/transforms/inline.py
@@ -41,8 +41,7 @@ class _ReferenceManager:
         # inlined_name -> use_count
         self.use_count = dict()
         self.rpc_mapper = _HostObjectMapper()
-        # exceptions 0-1023 are for runtime
-        self.exception_mapper = _HostObjectMapper(1024)
+        self.exception_mapper = _HostObjectMapper(core_language.first_user_eid)
         self.kernel_attr_init = []
 
         # reserved names