diff --git a/lib/Label.pm b/lib/Label.pm
index 52f9b7707..bc58b2d8b 100644
--- a/lib/Label.pm
+++ b/lib/Label.pm
@@ -42,6 +42,9 @@ This module defines labels for the graph objects (WWPlot).
 package Label;
 
 use strict;
+use warnings;
+
+use GD;
 
 #use Exporter;
 #use DynaLoader;
diff --git a/lib/Plots/Axes.pm b/lib/Plots/Axes.pm
index 8c7b08efc..24bff5e61 100644
--- a/lib/Plots/Axes.pm
+++ b/lib/Plots/Axes.pm
@@ -190,6 +190,9 @@ be visible after the fill, otherwise the fill will cover the axis. Default: 0
 
 package Plots::Axes;
 
+use strict;
+use warnings;
+
 sub new {
 	my $class = shift;
 	my $self  = {
diff --git a/lib/Plots/Data.pm b/lib/Plots/Data.pm
index b0a4580dc..1c365b006 100644
--- a/lib/Plots/Data.pm
+++ b/lib/Plots/Data.pm
@@ -107,6 +107,9 @@ to add / change the styles.
 
 package Plots::Data;
 
+use strict;
+use warnings;
+
 sub new {
 	my $class = shift;
 	my $self  = {
diff --git a/lib/Plots/GD.pm b/lib/Plots/GD.pm
index 00caae375..287689916 100644
--- a/lib/Plots/GD.pm
+++ b/lib/Plots/GD.pm
@@ -23,6 +23,11 @@ See L<plots.pl> for more details.
 
 package Plots::GD;
 
+use GD;
+
+use strict;
+use warnings;
+
 sub new {
 	my ($class, $pgplot) = @_;
 	my $self = {
diff --git a/lib/Plots/Plot.pm b/lib/Plots/Plot.pm
index 7fadd7578..be88b27f4 100644
--- a/lib/Plots/Plot.pm
+++ b/lib/Plots/Plot.pm
@@ -23,14 +23,17 @@ See L<plots.pl> for more details.
 
 package Plots::Plot;
 
+use strict;
+use warnings;
+
 use Plots::Axes;
 use Plots::Data;
-use Plots::GD;
 use Plots::Tikz;
+use Plots::GD;
 
 sub new {
 	my ($class, $pg, @opts) = @_;
-	my $size  = $main::envir{onTheFlyImageSize} || 500;
+	my $size  = $pg->{envir}{onTheFlyImageSize} || 500;
 
 	my $self = {
 		pg => $pg,
@@ -158,7 +161,7 @@ sub image_type {
 # Tikz needs to use pdf for hardcopy generation.
 sub ext {
 	my $self = shift;
-	return 'pdf' if ($self->{type} eq 'Tikz' && $main::displayMode eq 'TeX');
+	return 'pdf' if ($self->{type} eq 'Tikz' && $self->{pg}{displayMode} eq 'TeX');
 	return $self->{ext};
 }
 
@@ -166,7 +169,7 @@ sub ext {
 # Set $plot->{tikzDebug} to 1 to just generate the tikzCode, and not create a graph.
 sub tikz_code {
 	my $self = shift;
-	return ($self->{tikzCode} && $main::displayMode =~ /HTML/) ? '<pre>' . $self->{tikzCode} . '</pre>' : '';
+	return ($self->{tikzCode} && $self->{pg}{displayMode} =~ /HTML/) ? '<pre>' . $self->{tikzCode} . '</pre>' : '';
 }
 
 # Add functions to the graph.
diff --git a/lib/Plots/Tikz.pm b/lib/Plots/Tikz.pm
index b63948582..6e05a0d34 100644
--- a/lib/Plots/Tikz.pm
+++ b/lib/Plots/Tikz.pm
@@ -24,6 +24,9 @@ See L<plots.pl> for more details.
 
 package Plots::Tikz;
 
+use strict;
+use warnings;
+
 sub new {
 	my ($class, $pgplot) = @_;
 	my $image = new LaTeXImage;
diff --git a/lib/WWPlot.pm b/lib/WWPlot.pm
index 1b73e350e..2b9fd2467 100644
--- a/lib/WWPlot.pm
+++ b/lib/WWPlot.pm
@@ -169,6 +169,9 @@ These functions translate from real world to pixel coordinates.
 package WWPlot;
 
 use strict;
+use warnings;
+
+use GD;
 
 #use Exporter;
 #use DynaLoader;