diff --git a/DESCRIPTION b/DESCRIPTION
index d4b6d729ff..fb055cbdde 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -1,6 +1,6 @@
 Package: plotly
 Title: Create Interactive Web Graphics via 'plotly.js'
-Version: 3.4.14
+Version: 3.4.15
 Authors@R: c(person("Carson", "Sievert", role = c("aut", "cre"),
     email = "cpsievert1@gmail.com"),
     person("Chris", "Parmer", role = c("aut", "cph"),
diff --git a/NEWS b/NEWS
index 1b72caa9fe..4bacc828a3 100644
--- a/NEWS
+++ b/NEWS
@@ -1,3 +1,9 @@
+3.4.15 -- 18 Apr 2016
+
+BUGFIX:
+
+The alpha in geom_smooth was incorrectly inheriting from other layers. See #551.
+
 3.4.14 -- 15 Apr 2016
 
 CHANGES:
diff --git a/R/ggplotly.R b/R/ggplotly.R
index 7670ec5489..ef99c243c3 100644
--- a/R/ggplotly.R
+++ b/R/ggplotly.R
@@ -209,6 +209,7 @@ gg2list <- function(p, width = NULL, height = NULL, tooltip = "all", source = "A
   # attach a new column (hovertext) to each layer of data that should get mapped
   # to the text trace property
   data <- Map(function(x, y) {
+    if (nrow(x) == 0) return(x)
     # make sure the relevant aes exists in the data
     for (i in seq_along(y)) {
       aesName <- names(y)[[i]]
diff --git a/R/layers2traces.R b/R/layers2traces.R
index c53a06126e..febe2935fc 100644
--- a/R/layers2traces.R
+++ b/R/layers2traces.R
@@ -141,7 +141,8 @@ to_basic.GeomBoxplot <- function(data, prestats_data, layout, params, p, ...) {
 #' @export
 to_basic.GeomSmooth <- function(data, prestats_data, layout, params, p, ...) {
   dat <- prefix_class(data, "GeomPath")
-  dat$alpha <- NULL
+  # alpha for the path is always 1 (see GeomSmooth$draw_key)
+  dat$alpha <- 1
   if (!identical(params$se, FALSE)) {
     dat2 <- prefix_class(ribbon_dat(data), c("GeomPolygon", "GeomSmooth"))
     dat2$colour <- NULL