diff --git a/libavcodec/pcx.c b/libavcodec/pcx.c
index df6a8aa74a..51c9acf247 100644
--- a/libavcodec/pcx.c
+++ b/libavcodec/pcx.c
@@ -71,6 +71,7 @@ static void pcx_palette(const uint8_t **src, uint32_t *dst, unsigned int pallen)
 
     for (i=0; i<pallen; i++)
         *dst++ = bytestream_get_be24(src);
+    if (pallen < 256)
     memset(dst, 0, (256 - pallen) * sizeof(*dst));
 }