diff --git a/test/pdf-operators-text.c b/test/pdf-operators-text.c
index 556b9d7d8..6d654d115 100644
--- a/test/pdf-operators-text.c
+++ b/test/pdf-operators-text.c
@@ -127,6 +127,7 @@ draw (cairo_t *cr, int width, int height)
     cairo_set_font_size (cr, FONT_SIZE);
 
     text = malloc (strlen(WORD) * NUM_WORDS + 1);
+    text[0] = '\0';
     for (i = 0; i < NUM_WORDS; i++)
 	strcat (text, WORD);