diff --git a/src/ChunkedIO.cc b/src/ChunkedIO.cc
index d2eff510ce..d54b4eb70b 100644
--- a/src/ChunkedIO.cc
+++ b/src/ChunkedIO.cc
@@ -195,7 +195,7 @@ bool ChunkedIOFd::WriteChunk(Chunk* chunk, bool partial)
 	assert(chunk->len <= BUFFER_SIZE - sizeof(uint32) );
 
 	if ( chunk->len == 0 )
-		reporter->InternalError("attempt to write 0 bytes chunk");
+		InternalError("attempt to write 0 bytes chunk");
 
 	if ( partial )
 		chunk->len |= FLAG_PARTIAL;
@@ -285,7 +285,7 @@ bool ChunkedIOFd::FlushWriteBuffer()
 			}
 
 		if ( written == 0 )
-			reporter->InternalError("written==0");
+			InternalError("written==0");
 
 		// Short write.
 		write_pos += written;
@@ -906,7 +906,7 @@ bool ChunkedIOSSL::WriteData(char* p, uint32 len, bool* error)
 			return false;
 	}
 
-	reporter->InternalError("can't be reached");
+	InternalError("can't be reached");
 	return false;
 	}
 
@@ -1026,7 +1026,7 @@ bool ChunkedIOSSL::ReadData(char* p, uint32 len, bool* error)
 		}
 
 	// Can't be reached.
-	reporter->InternalError("can't be reached");
+	InternalError("can't be reached");
 	return false;
 	}
 
diff --git a/src/ChunkedIO.h b/src/ChunkedIO.h
index 516f0f7ddc..1f946c18ba 100644
--- a/src/ChunkedIO.h
+++ b/src/ChunkedIO.h
@@ -120,6 +120,11 @@ public:
 #endif
 
 protected:
+	void InternalError(const char* msg)
+		// We can't use the reporter here as we might be running in a
+		// sub-process.
+		{ fprintf(stderr, "%s", msg); abort(); }
+
 	Statistics stats;
 	const char* tag;
 
diff --git a/src/RemoteSerializer.cc b/src/RemoteSerializer.cc
index c4869e4328..af52683b76 100644
--- a/src/RemoteSerializer.cc
+++ b/src/RemoteSerializer.cc
@@ -2375,7 +2375,7 @@ bool RemoteSerializer::FlushPrintBuffer(Peer* p)
 	if ( p->state == Peer::CLOSING )
 		return false;
 
-	if ( ! p->print_buffer )
+	if ( ! (p->print_buffer && p->print_buffer_used) )
 		return true;
 
 	SendToChild(MSG_REMOTE_PRINT, p, p->print_buffer, p->print_buffer_used);
@@ -3407,11 +3407,11 @@ bool SocketComm::ProcessParentMessage()
 			}
 
 		default:
-			reporter->InternalError("unknown msg type %d", parent_msgtype);
+			InternalError(fmt("unknown msg type %d", parent_msgtype));
 			return true;
 		}
 
-		reporter->InternalError("cannot be reached");
+		InternalError("cannot be reached");
 		}
 
 	case ARGS:
@@ -3434,10 +3434,10 @@ bool SocketComm::ProcessParentMessage()
 		}
 
 	default:
-		reporter->InternalError("unknown msgstate");
+		InternalError("unknown msgstate");
 	}
 
-	reporter->InternalError("cannot be reached");
+	InternalError("cannot be reached");
 	return false;
 	}
 
@@ -3496,7 +3496,7 @@ bool SocketComm::DoParentMessage()
 			peers[j]->io->DumpDebugData(fmt("comm-dump.child.peer.%d", id), false);
 			}
 #else
-		reporter->InternalError("DEBUG_DUMP support not compiled in");
+		InternalError("DEBUG_DUMP support not compiled in");
 #endif
 		return true;
 		}
@@ -3556,10 +3556,10 @@ bool SocketComm::DoParentMessage()
 		return ForwardChunkToPeer();
 
 	default:
-		reporter->InternalError("ProcessParentMessage: unexpected state");
+		InternalError("ProcessParentMessage: unexpected state");
 	}
 
-	reporter->InternalError("cannot be reached");
+	InternalError("cannot be reached");
 	return false;
 	}
 
@@ -3620,7 +3620,7 @@ bool SocketComm::ProcessListen()
 bool SocketComm::ProcessParentCompress()
 	{
 #ifndef HAVE_LIBZ
-	reporter->InternalError("supposed to enable compression but don't have zlib");
+	InternalError("supposed to enable compression but don't have zlib");
 	return false;
 #else
 
@@ -3740,11 +3740,10 @@ bool SocketComm::ProcessRemoteMessage(SocketComm::Peer* peer)
 		}
 
 	default:
-		reporter->InternalError("ProcessRemoteMessage: unexpected state");
+		InternalError("ProcessRemoteMessage: unexpected state");
 	}
 
-	assert(false); // Cannot be reached.
-	return false;
+	return true;
 	}
 
 bool SocketComm::ForwardChunkToParent(Peer* peer, ChunkedIO::Chunk* c)
@@ -4051,6 +4050,12 @@ void SocketComm::Log(const char* msg, Peer* peer)
 	DEBUG_COMM(fmt("child: %s", buffer));
 	}
 
+void SocketComm::InternalError(const char* msg)
+	{
+	fprintf(stderr, "interal error in child: %s\n", msg);
+	Kill();
+	}
+
 void SocketComm::Kill()
 	{
 	if ( killing )
diff --git a/src/RemoteSerializer.h b/src/RemoteSerializer.h
index 20886544c6..68e7dfa0c7 100644
--- a/src/RemoteSerializer.h
+++ b/src/RemoteSerializer.h
@@ -463,6 +463,9 @@ protected:
 	// Check whether everything has been sent out.
 	void CheckFinished();
 
+	// Reports the error and terminates the process.
+	void InternalError(const char* msg);
+
 	// Communication helpers.
 	bool SendToParent(char type, Peer* peer, const char* str, int len = -1);
 	bool SendToParent(char type, Peer* peer, int nargs, ...); // can send uints32 only