157c157
<       if (!emptyString(rowtitles[x]))
---
>       if (rowtitles && !emptyString(rowtitles[x]))
159c159
<       matrix->rowtitle[x] = char2Chtype (rowtitles[x],
---
>       matrix->rowtitle[x] = char2Chtype (rowtitles?rowtitles[x]:0,
220c220
<       if (!emptyString(coltitles[x]))
---
>       if (coltitles && !emptyString(coltitles[x]))
222c222
<       matrix->coltitle[x] = char2Chtype (coltitles[x],
---
>       matrix->coltitle[x] = char2Chtype (coltitles?coltitles[x]:0,