diff --git a/libavcodec/exr.c b/libavcodec/exr.c
index f9525ecf02..6251fb76fd 100644
--- a/libavcodec/exr.c
+++ b/libavcodec/exr.c
@@ -322,7 +322,7 @@ static uint16_t reverse_lut(const uint8_t *bitmap, uint16_t *lut)
 
     i = k - 1;
 
-    memset(lut + k, 0, (USHORT_RANGE - k) * 2);
+    memset(lut + k * 2, 0, (USHORT_RANGE - k) * 2);
 
     return i;
 }