diff --git a/girepository/giconstantinfo.c b/girepository/giconstantinfo.c
index 69e103ba0..e08455809 100644
--- a/girepository/giconstantinfo.c
+++ b/girepository/giconstantinfo.c
@@ -108,9 +108,9 @@ gi_constant_info_free_value (GIConstantInfo *info,
  * The size of the constant value stored in @argument will be returned.
  * Free the value with gi_constant_info_free_value().
  *
- * Returns: size of the constant
+ * Returns: size of the constant, in bytes
  */
-gint
+gsize
 gi_constant_info_get_value (GIConstantInfo *info,
                             GIArgument     *value)
 {
diff --git a/girepository/giconstantinfo.h b/girepository/giconstantinfo.h
index 56c2cc85d..4b4b882a2 100644
--- a/girepository/giconstantinfo.h
+++ b/girepository/giconstantinfo.h
@@ -50,6 +50,6 @@ void         gi_constant_info_free_value (GIConstantInfo *info,
                                           GIArgument     *value);
 
 GI_AVAILABLE_IN_ALL
-gint         gi_constant_info_get_value (GIConstantInfo *info,
+gsize        gi_constant_info_get_value (GIConstantInfo *info,
                                          GIArgument     *value);
 G_END_DECLS