diff --git a/include/libi3.h b/include/libi3.h
index 91395328..9a276571 100644
--- a/include/libi3.h
+++ b/include/libi3.h
@@ -196,7 +196,7 @@ i3String *i3string_from_markup(const char *from_markup);
 
 /**
  * Build an i3String from an UTF-8 encoded string with fixed length.
- * To be used when no proper NUL-terminaison is available.
+ * To be used when no proper NULL-termination is available.
  * Returns the newly-allocated i3String.
  *
  */
diff --git a/libi3/string.c b/libi3/string.c
index f78a140f..a078b33e 100644
--- a/libi3/string.c
+++ b/libi3/string.c
@@ -48,7 +48,7 @@ i3String *i3string_from_markup(const char *from_markup) {
 
 /*
  * Build an i3String from an UTF-8 encoded string with fixed length.
- * To be used when no proper NUL-terminaison is available.
+ * To be used when no proper NULL-termination is available.
  * Returns the newly-allocated i3String.
  *
  */