diff --git a/R/image-interact.R b/R/image-interact.R
index cad6291ea..502b1fcf0 100644
--- a/R/image-interact.R
+++ b/R/image-interact.R
@@ -86,6 +86,8 @@ brushedPoints <- function(df, brush, xvar = NULL, yvar = NULL,
   if (use_x) {
     if (is.null(xvar))
       stop("brushedPoints: not able to automatically infer `xvar` from brush")
+    if (!(xvar %in% names(df)))
+      stop("brushedPoints: `xvar` ('", xvar ,"')  not in names of input")
     # Extract data values from the data frame
     x <- asNumber(df[[xvar]])
     keep_rows <- keep_rows & (x >= brush$xmin & x <= brush$xmax)
@@ -93,6 +95,8 @@ brushedPoints <- function(df, brush, xvar = NULL, yvar = NULL,
   if (use_y) {
     if (is.null(yvar))
       stop("brushedPoints: not able to automatically infer `yvar` from brush")
+    if (!(yvar %in% names(df)))
+      stop("brushedPoints: `yvar` ('", yvar ,"') not in names of input")
     y <- asNumber(df[[yvar]])
     keep_rows <- keep_rows & (y >= brush$ymin & y <= brush$ymax)
   }
@@ -245,6 +249,11 @@ nearPoints <- function(df, coordinfo, xvar = NULL, yvar = NULL,
   if (is.null(yvar))
     stop("nearPoints: not able to automatically infer `yvar` from coordinfo")
 
+  if (!(xvar %in% names(df)))
+    stop("nearPoints: `xvar` ('", xvar ,"')  not in names of input")
+  if (!(yvar %in% names(df)))
+    stop("nearPoints: `yvar` ('", yvar ,"')  not in names of input")
+
   # Extract data values from the data frame
   x <- asNumber(df[[xvar]])
   y <- asNumber(df[[yvar]])