Dequeismo is an improper use of the preposition de before the conjunction que in Spanish when the preposition is not required by any word in the sentence and needs an immediate grammar correction.

The opposite phenomenon, not using de after que when the rule requires it, is called queismo and it is one of the most frequent grammatical errors.

Situations in which Dequeismo Occurs

1. De + subordinate clause with attributive functions with the verb ser:

Incorrect: Lo que Juan quiere es de que vengas.

Correct: Lo que Juan quiere es que vengas.

(What Juan wants is for you to come.)

2. De + subject noun subordinate clause:

Incorrect: No entiendo de que no hayas terminado los deberes.

Correct: No entiendo que no hayas terminado los deberes.

(I don’t understand that you haven’t finished your homework.)

3. De + inappropriate preposition:

Incorrecto: Pensé de que vinieras.

Correcto: Pensé en que vinieras.

(I thought about you coming.)

4. De + verbs of speech:

Incorrect: Te comunico de que tienes cita mañana.

Correct: Te comunico que tienes cita mañana.

(I inform you that you have an appointment tomorrow.)

5. De + conjunctive locutions without a preposition:

Incorrect:  Una vez de que llegues, haremos la cena.

Correct: Una vez que llegues, haremos la cena.

(Once you arrive, we will have dinner.)

Examples of Dequeismo

Mind you! They are all INCORRECT:

1. Opinaba de que tenía razón. (He believed he was right.)

2. Creo de que es lo más justo para todos. (I think it’s the fairest thing for everyone.)

3. Pienso de que podrías acompañarle al cine. (I think you could go with him to the cinema.)

4. Le comunico de que debe acudir a la cita cinco minutos antes. (I’ll tell him that he has to be there five minutes early.)

5. Los bomberos impidieron de que el fuego destruyera la casa. (The firemen prevented the fire from destroying the house.)

6. Me imagino de que tengo más dinero en casa. (I think I have more money at home.)

7. Te aconsejo de que trabajes ahora todo lo que sea posible. (I advise you to work as much as possible now.)

8. Le pidió de que dejara de decir tonterías. (He asked her to stop talking nonsense.)

9. El objetivo fue de que viniera el máximo posible de gente. (The aim was to get as many people as possible to come.)

10. Confío de que ganará la competición. (I am confident that he will win the competition.)

Learn Spanish Grammar

It is not complicated at all, it is simply a matter of following the Spanish language course and practising some exercises about que in Spanish.

The dequeismo grammatical errors occur in many Spanish-speaking areas and are used by many native Spanish speakers. For example, in the south of Santiago de Chile, dequeismo is often used. In the eastern part of Spain, around Valencia, as well. We can find some studies of the phenomenon in the cultured areas of Havana, Cuba.

Finally, here are two tricks that will help you to identify the dequeismo without having to think too much about the grammar correction:

1. Turn the sentence into a question:

¿De qué piensas?  (What are you thinking about?)

Indeed, there is a dequeismo here.

2. Replace the noun subordinate clause with “eso” (that):

Pienso de eso. (I think of that.) Of course, there is a dequeismo here too!