I wrapped this function how i normally do which is usually correct the function im wrapping is here...info at least and a small example of its usage is there also at the end of the postl ;; CvFont cvFontQt(const char* nameFont, int pointSize = -1, CvScalar color = cvScalarAll(0), int weight = CV_FONT_NORMAL, ;; int style = CV_STYLE_NORMAL, int spacing = 0) (cffi:defcfun ("cvFontQt" %font-qt) (:struct cv-font)   (name-font :string)   (point-size :int)   (color (:struct cv-scalar))   (weight :int)   (style :int)   (spacing :int))   (defun font-qt (name-font &optional (point-size -1) (color (scalar-all 0)) (weight +font-normal+)                    (style +style-normal+) (spacing 0))   "Creates the font to draw a text on an image."              (%font-qt name-font point-size color weight style spacing)) im getting this error message when i run each of these  (with-foreign-object (font '(:struct cv-font))           (setf (mem-ref font `(:pointer (:struct cv-font))) (font-qt "Monospace"))) (defparameter  font (foreign-alloc '(:struct cv-font) :initial-element (list (font-qt ""))))  (font-qt "") There is no applicable method for the generic function   #<STANDARD-GENERIC-FUNCTION TRANSLATE-INTO-FOREIGN-MEMORY (5)> when called with arguments   ("" #<CFFI::FOREIGN-STRING-TYPE :UTF-8>    #.(SB-SYS:INT-SAP #X7FFFE1467FF0)).    [Condition of type SIMPLE-ERROR] it seems to be written right and I'm just running the function so i could use a little help on this . I never use any of cffi foreign-string functions for const char* just :string and they always run right