diff --git a/t/cooling.t b/t/cooling.t
index 0f0aef618..1317f1dce 100644
--- a/t/cooling.t
+++ b/t/cooling.t
@@ -2,7 +2,7 @@ use Test::More;
 use strict;
 use warnings;
 
-plan tests => 13;
+plan tests => 15;
 
 BEGIN {
     use FindBin;
@@ -32,7 +32,7 @@ sub buffer {
     $gcodegen = Slic3r::GCode->new;
     $gcodegen->apply_print_config($print_config);
     $gcodegen->set_layer_count(10);
-    $gcodegen->set_elapsed_time(0);
+    $gcodegen->set_extruders([ 0 ]);
     return Slic3r::GCode::CoolingBuffer->new($gcodegen);
 }
 
@@ -124,6 +124,18 @@ $config->set('disable_fan_first_layers',    [ 0 ]);
     like $gcode, qr/M106/, 'fan is activated on all objects printing at different Z';
 }
 
+{
+    my $buffer = buffer($config, {
+            'cooling'                   => [ 1               , 0                ],
+            'fan_below_layer_time'      => [ $print_time2 + 1, $print_time2 + 1 ], 
+            'slowdown_below_layer_time' => [ $print_time2 + 2, $print_time2 + 2 ]
+        });
+    $buffer->gcodegen->set_extruders([ 0, 1 ]);
+    my $gcode = $buffer->process_layer($gcode1 . "T1\nG1 X0 E1 F3000\n", 0);
+    like $gcode, qr/^M106/, 'fan is activated for the 1st tool';
+    like $gcode, qr/.*M107/, 'fan is disabled for the 2nd tool';
+}
+
 {
     my $config = Slic3r::Config->new_from_defaults;
     $config->set('cooling', [ 1 ]);
diff --git a/xs/src/libslic3r/GCode.hpp b/xs/src/libslic3r/GCode.hpp
index c09ee68a4..51ab5eb84 100644
--- a/xs/src/libslic3r/GCode.hpp
+++ b/xs/src/libslic3r/GCode.hpp
@@ -143,8 +143,6 @@ public:
     // For Perl bindings, to be used exclusively by unit tests.
     unsigned int    layer_count() const { return m_layer_count; }
     void            set_layer_count(unsigned int value) { m_layer_count = value; }
-	float           elapsed_time() const { return m_writer.elapsed_time()->total; }
-	void            set_elapsed_time(float value) { std::vector<unsigned int> extruders; extruders.push_back(0); m_writer.set_extruders(extruders); m_writer.set_extruder(0); m_writer.elapsed_time()->total = value; }
     void            apply_print_config(const PrintConfig &print_config);
 
 protected:
diff --git a/xs/src/libslic3r/GCode/CoolingBuffer.cpp b/xs/src/libslic3r/GCode/CoolingBuffer.cpp
index 55016846d..e5ea38fcb 100644
--- a/xs/src/libslic3r/GCode/CoolingBuffer.cpp
+++ b/xs/src/libslic3r/GCode/CoolingBuffer.cpp
@@ -237,6 +237,7 @@ std::string CoolingBuffer::process_layer(const std::string &gcode, size_t layer_
                 active_speed_modifier = size_t(-1);
             } else if (boost::starts_with(sline, toolchange_prefix)) {
                 // Switch the tool.
+                line.type = Adjustment::Line::TYPE_SET_TOOL;
                 unsigned int new_extruder = (unsigned int)atoi(sline.c_str() + toolchange_prefix.size());
                 if (new_extruder != m_current_extruder) {
                     m_current_extruder = new_extruder;
@@ -417,6 +418,7 @@ std::string CoolingBuffer::process_layer(const std::string &gcode, size_t layer_
                 m_current_extruder = new_extruder;
                 change_extruder_set_fan();
             }
+            new_gcode.append(gcode.c_str() + line->line_start, line->line_end - line->line_start);
         } else if (line->type & Adjustment::Line::TYPE_BRIDGE_FAN_START) {
             if (bridge_fan_control)
                 new_gcode += m_gcodegen.writer().set_fan(bridge_fan_speed, true) + "\n";
diff --git a/xs/xsp/GCode.xsp b/xs/xsp/GCode.xsp
index 256799897..9104e481a 100644
--- a/xs/xsp/GCode.xsp
+++ b/xs/xsp/GCode.xsp
@@ -38,8 +38,8 @@
 
     unsigned int    layer_count() const;
     void            set_layer_count(unsigned int value);
-    float           elapsed_time() const;
-    void            set_elapsed_time(float value);
+    void            set_extruders(std::vector<unsigned int> extruders) 
+        %code{% THIS->writer().set_extruders(extruders); THIS->writer().set_extruder(0); %};
 
     void apply_print_config(StaticPrintConfig* print_config)
         %code{%