diff --git a/src/client/windows/crash_generation/crash_generation_server.cc b/src/client/windows/crash_generation/crash_generation_server.cc
index b98fb5e0..b4bb5c95 100644
--- a/src/client/windows/crash_generation/crash_generation_server.cc
+++ b/src/client/windows/crash_generation/crash_generation_server.cc
@@ -85,6 +85,15 @@ static bool IsClientRequestValid(const ProtocolMessage& msg) {
           msg.assert_info != NULL);
 }
 
+#ifdef _DEBUG
+static bool CheckForIOIncomplete(bool success) {
+  // We should never get an I/O incomplete since we should not execute this
+  // unless the operation has finished and the overlapped event is signaled. If
+  // we do get INCOMPLETE, we have a bug in our code.
+  return success ? false : (GetLastError() == ERROR_IO_INCOMPLETE);
+}
+#endif
+
 CrashGenerationServer::CrashGenerationServer(
     const std::wstring& pipe_name,
     SECURITY_ATTRIBUTES* pipe_sec_attrs,
@@ -388,18 +397,13 @@ void CrashGenerationServer::HandleReadingState() {
                                      &overlapped_,
                                      &bytes_count,
                                      FALSE) != FALSE;
-  DWORD error_code = success ? ERROR_SUCCESS : GetLastError();
-
   if (success && bytes_count == sizeof(ProtocolMessage)) {
     EnterStateImmediately(IPC_SERVER_STATE_READ_DONE);
-  } else {
-    // We should never get an I/O incomplete since we should not execute this
-    // unless the Read has finished and the overlapped event is signaled. If
-    // we do get INCOMPLETE, we have a bug in our code.
-    assert(error_code != ERROR_IO_INCOMPLETE);
-
-    EnterStateImmediately(IPC_SERVER_STATE_DISCONNECTING);
+    return;
   }
+
+  assert(!CheckForIOIncomplete(success));
+  EnterStateImmediately(IPC_SERVER_STATE_DISCONNECTING);
 }
 
 // When the server thread serving the client is in the READ_DONE state,
@@ -468,18 +472,12 @@ void CrashGenerationServer::HandleWritingState() {
                                      &overlapped_,
                                      &bytes_count,
                                      FALSE) != FALSE;
-  DWORD error_code = success ? ERROR_SUCCESS : GetLastError();
-
   if (success) {
     EnterStateImmediately(IPC_SERVER_STATE_WRITE_DONE);
     return;
   }
 
-  // We should never get an I/O incomplete since we should not execute this
-  // unless the Write has finished and the overlapped event is signaled. If
-  // we do get INCOMPLETE, we have a bug in our code.
-  assert(error_code != ERROR_IO_INCOMPLETE);
-
+  assert(!CheckForIOIncomplete(success));
   EnterStateImmediately(IPC_SERVER_STATE_DISCONNECTING);
 }
 
@@ -517,8 +515,6 @@ void CrashGenerationServer::HandleReadingAckState() {
                                      &overlapped_,
                                      &bytes_count,
                                      FALSE) != FALSE;
-  DWORD error_code = success ? ERROR_SUCCESS : GetLastError();
-
   if (success) {
     // The connection handshake with the client is now complete; perform
     // the callback.
@@ -551,10 +547,7 @@ void CrashGenerationServer::HandleReadingAckState() {
       }
     }
   } else {
-    // We should never get an I/O incomplete since we should not execute this
-    // unless the Read has finished and the overlapped event is signaled. If
-    // we do get INCOMPLETE, we have a bug in our code.
-    assert(error_code != ERROR_IO_INCOMPLETE);
+    assert(!CheckForIOIncomplete(success));
   }
 
   EnterStateImmediately(IPC_SERVER_STATE_DISCONNECTING);