diff --git a/src/dec/buffer_dec.c b/src/dec/buffer_dec.c
index 75eb3c4..3cd94eb 100644
--- a/src/dec/buffer_dec.c
+++ b/src/dec/buffer_dec.c
@@ -74,7 +74,8 @@
   } else {    // RGB checks
     const WebPRGBABuffer* const buf = &buffer->u.RGBA;
     const int stride = abs(buf->stride);
-    const uint64_t size = MIN_BUFFER_SIZE(width, height, stride);
+    const uint64_t size =
+        MIN_BUFFER_SIZE(width * kModeBpp[mode], height, stride);
     ok &= (size <= buf->size);
     ok &= (stride >= width * kModeBpp[mode]);
     ok &= (buf->rgba != NULL);