diff --git a/misc-scripts/density_feature/vega_gene_density.pl b/misc-scripts/density_feature/vega_gene_density.pl
index d0a8540ebea3bac6bb53376d2e4516e22edb3b87..ae64cc7e6f76d52ac20bdbc130335616ebc60f5f 100755
--- a/misc-scripts/density_feature/vega_gene_density.pl
+++ b/misc-scripts/density_feature/vega_gene_density.pl
@@ -237,7 +237,7 @@ foreach my $object ($big_chr, $small_chr) {
 		print STDERR join(",", map { $num{$gene_types{$_}} || 0 }
 				  sort keys %gene_types);
 		print STDERR " | ";
-		print STDERR "Mem: " . `ps $$ -o vsz |tail -1`;
+		print STDERR "Mem: " . `ps -p $$ -o vsz |tail -1`;
 	    }
 	    
 	    
diff --git a/modules/Bio/EnsEMBL/Utils/ConversionSupport.pm b/modules/Bio/EnsEMBL/Utils/ConversionSupport.pm
index f8585eec5b756ddc9b3f1dec7b2d6f9d09ccf488..d5131361177855b4e025dc4b529bd502ee10fb72 100644
--- a/modules/Bio/EnsEMBL/Utils/ConversionSupport.pm
+++ b/modules/Bio/EnsEMBL/Utils/ConversionSupport.pm
@@ -730,7 +730,7 @@ sub finish_log {
 
 sub date_and_mem {
     my $date = strftime "%Y-%m-%d %T", localtime;
-    my $mem = `ps $$ -o vsz |tail -1`;
+    my $mem = `ps -p $$ -o vsz |tail -1`;
     chomp $mem;
     return "[$date, mem $mem]";
 }
@@ -761,7 +761,7 @@ sub date {
 =cut
 
 sub mem {
-    my $mem = `ps $$ -o vsz |tail -1`;
+    my $mem = `ps -p $$ -o vsz |tail -1`;
     chomp $mem;
     return $mem;
 }