diff --git a/osbuild/host.py b/osbuild/host.py
index d2a406a3..5d278afd 100644
--- a/osbuild/host.py
+++ b/osbuild/host.py
@@ -48,7 +48,7 @@ import sys
 import threading
 import traceback
 from collections import OrderedDict
-from typing import Any, Dict, List, Optional, Tuple
+from typing import Any, Dict, List, Optional, Tuple, Callable
 
 from osbuild.util.jsoncomm import FdSet, Socket
 
@@ -131,6 +131,16 @@ class ServiceProtocol:
         # method call, which can also be `None`
         return data
 
+    @staticmethod
+    def encode_signal(sig: Any):
+        msg = {
+            "type": "signal",
+            "data": {
+                "reply": sig
+            }
+        }
+        return msg
+
     @staticmethod
     def encode_exception(value, tb):
         backtrace = "".join(traceback.format_tb(tb))
@@ -293,6 +303,10 @@ class Service(abc.ABC):
 
         return msg, fds
 
+    def emit_signal(self, data: Any, fds: Optional[list] = None):
+        self._check_fds(fds)
+        self.sock.send(self.protocol.encode_signal(data), fds=fds)
+
     @staticmethod
     def _close_all(fds: Optional[List[int]]):
         if not fds:
@@ -336,7 +350,8 @@ class ServiceClient:
 
     def call_with_fds(self, method: str,
                       args: Optional[Any] = None,
-                      fds: Optional[List] = None) -> Tuple[Any, FdSet]:
+                      fds: Optional[List] = None,
+                      on_signal: Callable[[Any, FdSet], None] = None) -> Tuple[Any, FdSet]:
         """
         Remotely call a method and return the result, including file
         descriptors.
@@ -344,16 +359,20 @@ class ServiceClient:
 
         msg = self.protocol.encode_method(method, args)
 
-        ret, fds, _ = self.sock.send_and_recv(msg, fds=fds)
+        self.sock.send(msg, fds=fds)
 
-        kind, data = self.protocol.decode_message(ret)
-
-        if kind == "reply":
-            ret = self.protocol.decode_reply(data)
-            return ret, fds
-        if kind == "exception":
-            error = self.protocol.decode_exception(data)
-            raise error
+        while True:
+            ret, fds, _ = self.sock.recv()
+            kind, data = self.protocol.decode_message(ret)
+            if kind == "signal":
+                ret = self.protocol.decode_reply(data)
+                on_signal(ret, fds)
+            if kind == "reply":
+                ret = self.protocol.decode_reply(data)
+                return ret, fds
+            if kind == "exception":
+                error = self.protocol.decode_exception(data)
+                raise error
 
         raise ProtocolError(f"unknown message type: {kind}")
 
diff --git a/test/mod/test_host.py b/test/mod/test_host.py
index d2157a2b..56ea1807 100755
--- a/test/mod/test_host.py
+++ b/test/mod/test_host.py
@@ -61,6 +61,18 @@ class ServiceTest(host.Service):
                         continue
                     raise
                 raise ValueError(f"fd '{fd}' was not closed")
+        elif method == "signal_me_3_times":
+            self.emit_signal(0)
+            self.emit_signal(1)
+            self.emit_signal(2)
+        elif method == "signal_me_on_fd":
+            with tempfile.TemporaryFile("w+") as f:
+                with os.fdopen(fds.steal(0)) as d:
+                    f.write(d.read())
+                f.seek(0)
+                fds = [os.dup(f.fileno())]
+                self.register_fds(fds)
+                self.emit_signal("that should do it", fds)
         else:
             raise host.ProtocolError("unknown method:", method)
 
@@ -135,6 +147,42 @@ def test_exception():
             client.call("exception")
 
 
+def test_signals():
+    with host.ServiceManager() as mgr:
+        exec_callback = 0
+
+        def check_value(item, _fds):
+            nonlocal exec_callback
+            assert item == exec_callback
+            exec_callback += 1
+        client = mgr.start("test_signal_me_3_times", __file__)
+        client.call_with_fds("signal_me_3_times", on_signal=check_value)
+        assert exec_callback == 3
+
+
+def test_signals_on_separate_fd():
+    with host.ServiceManager() as mgr:
+
+        data = "osbuild\n"
+        exec_callback = False
+
+        def check_value(item, fds):
+            nonlocal exec_callback
+            exec_callback = True
+            assert item == "that should do it"
+            with os.fdopen(fds.steal(0)) as d:
+                assert data == d.read()
+
+        client = mgr.start("test_signal_me_on_fd", __file__)
+
+        with tempfile.TemporaryFile("w+") as f:
+            f.write(data)
+            f.seek(0)
+
+            client.call_with_fds("signal_me_on_fd", fds=[f.fileno()], on_signal=check_value)
+        assert exec_callback
+
+
 def main():
     service = ServiceTest.from_args(sys.argv[1:])
     service.main()