diff --git a/src/libsysprof-analyze/sysprof-document-private.h b/src/libsysprof-analyze/sysprof-document-private.h
index a289a073..75f4a783 100644
--- a/src/libsysprof-analyze/sysprof-document-private.h
+++ b/src/libsysprof-analyze/sysprof-document-private.h
@@ -42,7 +42,7 @@ gboolean         _sysprof_document_symbolize_finish (SysprofDocument      *self,
                                                      GAsyncResult         *result,
                                                      GError              **error);
 gboolean         _sysprof_document_is_native        (SysprofDocument      *self);
-char            *_sysprof_document_ref_string       (SysprofDocument      *self,
+GRefString      *_sysprof_document_ref_string       (SysprofDocument      *self,
                                                      const char           *name);
 GtkBitset       *_sysprof_document_traceables       (SysprofDocument      *self);
 
diff --git a/src/libsysprof-analyze/sysprof-document.c b/src/libsysprof-analyze/sysprof-document.c
index 2e8911e8..83384564 100644
--- a/src/libsysprof-analyze/sysprof-document.c
+++ b/src/libsysprof-analyze/sysprof-document.c
@@ -525,7 +525,7 @@ _sysprof_document_new_finish (GAsyncResult  *result,
   return ret;
 }
 
-char *
+GRefString *
 _sysprof_document_ref_string (SysprofDocument *self,
                               const char      *name)
 {