diff --git a/R/PlotEquiMap.R b/R/PlotEquiMap.R
index ee10ec3aa4f2c42947f1b286b03a4f1e4d683bbf..640533399ebb5ca5d485c11fa9edfb1954d245b2 100644
--- a/R/PlotEquiMap.R
+++ b/R/PlotEquiMap.R
@@ -748,9 +748,10 @@ PlotEquiMap <- function(var, lon, lat, varu = NULL, varv = NULL,
   # ~~~~~~~~~~~~~~~~~
   #
   latb <- sort(lat, index.return = TRUE)
-  dlon <- lon[2:dims[1]] - lon[1:(dims[1] - 1)]
+  dlon <- diff(lon)
   wher <- which(dlon > (mean(dlon) + 1))
   if (length(wher) > 0) {
+    warning("Detect gap in 'lon' vector, which is considered as crossing the border.")
     lon[(wher + 1):dims[1]] <- lon[(wher + 1):dims[1]] - 360
   }
   lonb <- sort(lon, index.return = TRUE)
@@ -942,7 +943,7 @@ PlotEquiMap <- function(var, lon, lat, varu = NULL, varv = NULL,
   #  Plotting continents
   # ~~~~~~~~~~~~~~~~~~~~~
   #
-  wrap_vec <- c(lon[1], lon[1] + 360)
+  wrap_vec <- c(lonb$x[1], lonb$x[1] + 360)
   old_lwd <- par('lwd')
   par(lwd = coast_width)
   # If [0, 360], use GEOmap; if [-180, 180], use maps::map