diff --git a/R/plot_NparOF.R b/R/plot_NparOF.R
index 223517739bc13fbaf5f35a4b4b1a8ee9d35765ad..29d0c56452c63f793d9c91bae105bdbe5fbc00b3 100755
--- a/R/plot_NparOF.R
+++ b/R/plot_NparOF.R
@@ -48,7 +48,7 @@ plot_NparOF <- function(params,
       stop("Missing argument: 'params' must be provided !!" )
       
     # Number of parameter sets
-    n <- nrow(params)
+    n <- NROW(params)
 
     # Checking 'gofs'
     if (missing(gofs)) {
diff --git a/R/plot_particles.R b/R/plot_particles.R
index 1b2dc2623a8fb4264c2fdaec064cba6127ab5450..c4bde5d068fef688bab456b4daf47ae48f3c4695 100755
--- a/R/plot_particles.R
+++ b/R/plot_particles.R
@@ -82,11 +82,17 @@ plot_particles <- function(#####################################################
   # Checking that 'params' exists
   if ( missing(params) ) stop( "Missing argument: 'params'" )
   
-  # Checking that 'gofs' exists
-  if ( missing(gofs) ) stop( "Missing argument: 'gofs'" )
-  
   # number of parameters
   nparam <- ncol(params)
+
+  # Number of parameter sets
+  n <- NROW(params)
+
+  # Checking 'gofs'
+  if (missing(gofs)) {
+    stop("Missing argument: 'gofs' must be provided !!" )
+  } else if (length(gofs) != n)
+      stop("Invalid argument: 'length(gofs) != nrow(params)' (", length(gofs), "!=", n, ") !!" )
   
   # Parameter names
   param.names <- colnames(params)