diff --git a/libavcodec/x264.c b/libavcodec/x264.c
index 0b08b2df80..b2e922f0a7 100644
--- a/libavcodec/x264.c
+++ b/libavcodec/x264.c
@@ -150,7 +150,7 @@ X264_init(AVCodecContext *avctx)
 
     if(avctx->flags & CODEC_FLAG_QSCALE && avctx->global_quality > 0)
         x4->params.rc.i_qp_constant =
-            12 + 6 * av_log2((double) avctx->global_quality / FF_QP2LAMBDA);
+            12 + 6 * log2((double) avctx->global_quality / FF_QP2LAMBDA);
 
     x4->params.i_width = avctx->width;
     x4->params.i_height = avctx->height;