diff --git a/subprojects/gstreamer/libs/gst/base/gstbasesrc.h b/subprojects/gstreamer/libs/gst/base/gstbasesrc.h
index 38c3ef3d8e..b1612dcafb 100644
--- a/subprojects/gstreamer/libs/gst/base/gstbasesrc.h
+++ b/subprojects/gstreamer/libs/gst/base/gstbasesrc.h
@@ -241,7 +241,7 @@ struct _GstBaseSrcClass {
 
   /**
    * GstBaseSrcClass::create:
-   * @buf: (inout):
+   * @buf: (inout) (nullable):
    *
    * Ask the subclass to create a buffer with @offset and @size, the default
    * implementation will call alloc if no allocated @buf is provided and then call fill.
@@ -250,7 +250,7 @@ struct _GstBaseSrcClass {
                                  GstBuffer **buf);
   /**
    * GstBaseSrcClass::alloc:
-   * @buf: (out):
+   * @buf: (out) (nullable):
    *
    * Ask the subclass to allocate an output buffer with @offset and @size, the default
    * implementation will use the negotiated allocator.
diff --git a/subprojects/gstreamer/libs/gst/base/gstpushsrc.h b/subprojects/gstreamer/libs/gst/base/gstpushsrc.h
index d0d8cef9b7..d987be2a63 100644
--- a/subprojects/gstreamer/libs/gst/base/gstpushsrc.h
+++ b/subprojects/gstreamer/libs/gst/base/gstpushsrc.h
@@ -72,7 +72,7 @@ struct _GstPushSrcClass {
 
   /**
    * GstPushSrcClass::create:
-   * @buf: (inout):
+   * @buf: (inout) (nullable):
    *
    * Ask the subclass to create a buffer, the default implementation will call alloc if
    * no allocated @buf is provided and then call fill.
@@ -80,7 +80,7 @@ struct _GstPushSrcClass {
   GstFlowReturn (*create) (GstPushSrc *src, GstBuffer **buf);
   /**
    * GstPushSrcClass::alloc:
-   * @buf: (out):
+   * @buf: (out) (nullable):
    *
    * Allocate memory for a buffer.
    */