diff --git a/app/src/tooloptionwidget.cpp b/app/src/tooloptionwidget.cpp
index 11fdba46f7..23e09e66c2 100644
--- a/app/src/tooloptionwidget.cpp
+++ b/app/src/tooloptionwidget.cpp
@@ -78,6 +78,7 @@ void ToolOptionWidget::updateUI()
     setPreserveAlpha(p.preserveAlpha);
     setVectorMergeEnabled(p.vectorMergeEnabled);
     setAA(p.useAA);
+    setFillMode(p.fillMode);
     setStabilizerLevel(p.stabilizerLevel);
     setTolerance(static_cast<int>(p.tolerance));
     setFillContour(p.useFillContour);
@@ -109,6 +110,8 @@ void ToolOptionWidget::makeConnectionToEditor(Editor* editor)
     connect(ui->vectorMergeBox, &QCheckBox::clicked, toolManager, &ToolManager::setVectorMergeEnabled);
     connect(ui->useAABox, &QCheckBox::clicked, toolManager, &ToolManager::setAA);
 
+    connect(ui->fillMode, static_cast<void (QComboBox::*)(int)>(&QComboBox::activated), toolManager, &ToolManager::setFillMode);
+
     connect(ui->inpolLevelsCombo, static_cast<void (QComboBox::*)(int)>(&QComboBox::activated), toolManager, &ToolManager::setStabilizerLevel);
 
     connect(ui->toleranceSlider, &SpinSlider::valueChanged, toolManager, &ToolManager::setTolerance);
@@ -135,6 +138,7 @@ void ToolOptionWidget::onToolPropertyChanged(ToolType, ToolPropertyType ePropert
     case PRESERVEALPHA: setPreserveAlpha(p.preserveAlpha); break;
     case VECTORMERGE: setVectorMergeEnabled(p.vectorMergeEnabled); break;
     case ANTI_ALIASING: setAA(p.useAA); break;
+    case FILL_MODE: setFillMode(p.fillMode); break;
     case STABILIZATION: setStabilizerLevel(p.stabilizerLevel); break;
     case TOLERANCE: setTolerance(static_cast<int>(p.tolerance)); break;
     case FILLCONTOUR: setFillContour(p.useFillContour); break;
@@ -157,6 +161,7 @@ void ToolOptionWidget::setVisibility(BaseTool* tool)
     ui->makeInvisibleBox->setVisible(tool->isPropertyEnabled(INVISIBILITY));
     ui->preserveAlphaBox->setVisible(tool->isPropertyEnabled(PRESERVEALPHA));
     ui->useAABox->setVisible(tool->isPropertyEnabled(ANTI_ALIASING));
+    ui->fillModeGroup->setVisible(tool->isPropertyEnabled(FILL_MODE));
     ui->stabilizerLabel->setVisible(tool->isPropertyEnabled(STABILIZATION));
     ui->inpolLevelsCombo->setVisible(tool->isPropertyEnabled(STABILIZATION));
     ui->toleranceSlider->setVisible(tool->isPropertyEnabled(TOLERANCE));
@@ -187,6 +192,7 @@ void ToolOptionWidget::setVisibility(BaseTool* tool)
             ui->sizeSlider->setLabel(tr("Stroke Thickness"));
             ui->toleranceSlider->setVisible(false);
             ui->toleranceSpinBox->setVisible(false);
+            ui->fillModeGroup->setVisible(false);
             break;
         default:
             ui->sizeSlider->setLabel(tr("Width"));
@@ -299,6 +305,11 @@ void ToolOptionWidget::setAA(int x)
     }
 }
 
+void ToolOptionWidget::setFillMode(int x)
+{
+    ui->fillMode->setCurrentIndex(qBound(0, x, ui->fillMode->count() - 1));
+}
+
 void ToolOptionWidget::setStabilizerLevel(int x)
 {
     ui->inpolLevelsCombo->setCurrentIndex(qBound(0, x, ui->inpolLevelsCombo->count() - 1));
@@ -341,6 +352,7 @@ void ToolOptionWidget::disableAllOptions()
     ui->preserveAlphaBox->hide();
     ui->vectorMergeBox->hide();
     ui->useAABox->hide();
+    ui->fillModeGroup->hide();
     ui->inpolLevelsCombo->hide();
     ui->toleranceSlider->hide();
     ui->toleranceSpinBox->hide();
diff --git a/app/src/tooloptionwidget.h b/app/src/tooloptionwidget.h
index 7733ac9929..968a1b263d 100644
--- a/app/src/tooloptionwidget.h
+++ b/app/src/tooloptionwidget.h
@@ -61,6 +61,7 @@ public slots:
     void setPreserveAlpha(int);
     void setVectorMergeEnabled(int);
     void setAA(int);
+    void setFillMode(int);
     void setStabilizerLevel(int);
     void setTolerance(int);
     void setFillContour(int);
diff --git a/app/ui/tooloptions.ui b/app/ui/tooloptions.ui
index 0b576fe525..0bcd20d442 100644
--- a/app/ui/tooloptions.ui
+++ b/app/ui/tooloptions.ui
@@ -47,21 +47,6 @@
        </rect>
       </property>
       <layout class="QVBoxLayout" name="verticalLayout">
-       <property name="spacing">
-        <number>6</number>
-       </property>
-       <property name="leftMargin">
-        <number>0</number>
-       </property>
-       <property name="topMargin">
-        <number>0</number>
-       </property>
-       <property name="rightMargin">
-        <number>0</number>
-       </property>
-       <property name="bottomMargin">
-        <number>2</number>
-       </property>
        <item>
         <layout class="QHBoxLayout" name="horizontalLayout_2">
          <item>
@@ -241,6 +226,54 @@
          </property>
         </widget>
        </item>
+       <item>
+        <widget class="QWidget" name="fillModeGroup" native="true">
+         <layout class="QHBoxLayout" name="horizontalLayout_5">
+          <property name="leftMargin">
+           <number>0</number>
+          </property>
+          <property name="topMargin">
+           <number>0</number>
+          </property>
+          <property name="rightMargin">
+           <number>0</number>
+          </property>
+          <property name="bottomMargin">
+           <number>0</number>
+          </property>
+          <item>
+           <widget class="QLabel" name="fillModeLabel">
+            <property name="text">
+             <string>Transparency</string>
+            </property>
+           </widget>
+          </item>
+          <item>
+           <widget class="QComboBox" name="fillMode">
+            <property name="sizePolicy">
+             <sizepolicy hsizetype="Expanding" vsizetype="Fixed">
+              <horstretch>0</horstretch>
+              <verstretch>0</verstretch>
+             </sizepolicy>
+            </property>
+            <property name="toolTip">
+             <string>Defines how the fill will behave when the new color is not opaque</string>
+            </property>
+            <item>
+             <property name="text">
+              <string>Overlay</string>
+             </property>
+            </item>
+            <item>
+             <property name="text">
+              <string>Replace</string>
+             </property>
+            </item>
+           </widget>
+          </item>
+         </layout>
+        </widget>
+       </item>
        <item>
         <layout class="QHBoxLayout" name="horizontalLayout_4" stretch="0,1">
          <item>
diff --git a/core_lib/src/graphics/bitmap/bitmapimage.cpp b/core_lib/src/graphics/bitmap/bitmapimage.cpp
index d5dc50ef8f..cdee543a32 100644
--- a/core_lib/src/graphics/bitmap/bitmapimage.cpp
+++ b/core_lib/src/graphics/bitmap/bitmapimage.cpp
@@ -790,16 +790,16 @@ bool BitmapImage::compareColor(QRgb newColor, QRgb oldColor, int tolerance, QHas
 
 // Flood fill
 // ----- http://lodev.org/cgtutor/floodfill.html
-void BitmapImage::floodFill(BitmapImage* targetImage,
+BitmapImage* BitmapImage::floodFill(BitmapImage* targetImage,
                             QRect cameraRect,
                             QPoint point,
-                            QRgb newColor,
+                            QRgb fillColor,
                             int tolerance)
 {
     // If the point we are supposed to fill is outside the image and camera bounds, do nothing
     if(!cameraRect.united(targetImage->bounds()).contains(point))
     {
-        return;
+        return nullptr;
     }
 
     // Square tolerance for use with compareColor
@@ -844,11 +844,11 @@ void BitmapImage::floodFill(BitmapImage* targetImage,
         spanLeft = spanRight = false;
         while (xTemp <= targetImage->mBounds.right() &&
                compareColor(targetImage->constScanLine(xTemp, point.y()), oldColor, tolerance, cache.data()) &&
-               newPlacedColor != newColor)
+               newPlacedColor != fillColor)
         {
 
             // Set pixel color
-            replaceImage->scanLine(xTemp, point.y(), newColor);
+            replaceImage->scanLine(xTemp, point.y(), fillColor);
 
             if (!spanLeft && (point.y() > targetImage->mBounds.top()) &&
                 compareColor(targetImage->constScanLine(xTemp, point.y() - 1), oldColor, tolerance, cache.data())) {
@@ -876,7 +876,5 @@ void BitmapImage::floodFill(BitmapImage* targetImage,
         }
     }
 
-    targetImage->paste(replaceImage);
-    targetImage->modification();
-    delete replaceImage;
+    return replaceImage;
 }
diff --git a/core_lib/src/graphics/bitmap/bitmapimage.h b/core_lib/src/graphics/bitmap/bitmapimage.h
index eb3552a262..02522db41d 100644
--- a/core_lib/src/graphics/bitmap/bitmapimage.h
+++ b/core_lib/src/graphics/bitmap/bitmapimage.h
@@ -75,7 +75,7 @@ class BitmapImage : public KeyFrame
     void clear(QRectF rectangle) { clear(rectangle.toRect()); }
 
     static inline bool compareColor(QRgb newColor, QRgb oldColor, int tolerance, QHash<QRgb, bool> *cache);
-    static void floodFill(BitmapImage* targetImage, QRect cameraRect, QPoint point, QRgb newColor, int tolerance);
+    static BitmapImage* floodFill(BitmapImage* targetImage, QRect cameraRect, QPoint point, QRgb newColor, int tolerance);
 
     void drawLine(QPointF P1, QPointF P2, QPen pen, QPainter::CompositionMode cm, bool antialiasing);
     void drawRect(QRectF rectangle, QPen pen, QBrush brush, QPainter::CompositionMode cm, bool antialiasing);
diff --git a/core_lib/src/managers/toolmanager.cpp b/core_lib/src/managers/toolmanager.cpp
index a28605a58d..91615def27 100644
--- a/core_lib/src/managers/toolmanager.cpp
+++ b/core_lib/src/managers/toolmanager.cpp
@@ -194,6 +194,12 @@ void ToolManager::setAA(int usingAA)
     emit toolPropertyChanged(currentTool()->type(), ANTI_ALIASING);
 }
 
+void ToolManager::setFillMode(int mode)
+{
+    currentTool()->setFillMode(mode);
+    emit toolPropertyChanged(currentTool()->type(), FILL_MODE);
+}
+
 void ToolManager::setStabilizerLevel(int level)
 {
     currentTool()->setStabilizerLevel(level);
diff --git a/core_lib/src/managers/toolmanager.h b/core_lib/src/managers/toolmanager.h
index 16666cef47..4a552f315f 100644
--- a/core_lib/src/managers/toolmanager.h
+++ b/core_lib/src/managers/toolmanager.h
@@ -66,6 +66,7 @@ public slots:
     void setBezier(bool);
     void setPressure(bool);
     void setAA(int);
+    void setFillMode(int);
     void setStabilizerLevel(int);
     void setTolerance(int);
     void setUseFillContour(bool);
diff --git a/core_lib/src/tool/basetool.cpp b/core_lib/src/tool/basetool.cpp
index fe7ba6ebe9..54890694a4 100644
--- a/core_lib/src/tool/basetool.cpp
+++ b/core_lib/src/tool/basetool.cpp
@@ -63,6 +63,7 @@ BaseTool::BaseTool(QObject* parent) : QObject(parent)
     mPropertyEnabled.insert(PRESERVEALPHA, false);
     mPropertyEnabled.insert(BEZIER, false);
     mPropertyEnabled.insert(ANTI_ALIASING, false);
+    mPropertyEnabled.insert(FILL_MODE, false);
     mPropertyEnabled.insert(STABILIZATION, false);
 }
 
@@ -443,6 +444,11 @@ void BaseTool::setAA(const int useAA)
     properties.useAA = useAA;
 }
 
+void BaseTool::setFillMode(const int mode)
+{
+    properties.fillMode = mode;
+}
+
 void BaseTool::setStabilizerLevel(const int level)
 {
     properties.stabilizerLevel = level;
diff --git a/core_lib/src/tool/basetool.h b/core_lib/src/tool/basetool.h
index 0334ac9986..2d1a87487e 100644
--- a/core_lib/src/tool/basetool.h
+++ b/core_lib/src/tool/basetool.h
@@ -47,6 +47,7 @@ class Properties
     bool  bezier_state = false;
     bool  useFeather = true;
     int   useAA = 0;
+    int   fillMode = 0;
     int   stabilizerLevel = 0;
     qreal tolerance = 0;
     bool  useFillContour = false;
@@ -113,6 +114,7 @@ class BaseTool : public QObject
     virtual void setPreserveAlpha(const bool preserveAlpha);
     virtual void setVectorMergeEnabled(const bool vectorMergeEnabled);
     virtual void setAA(const int useAA);
+    virtual void setFillMode(const int mode);
     virtual void setStabilizerLevel(const int level);
     virtual void setTolerance(const int tolerance);
     virtual void setUseFillContour(const bool useFillContour);
diff --git a/core_lib/src/tool/buckettool.cpp b/core_lib/src/tool/buckettool.cpp
index 8bd252ad63..ea0b6c58a7 100644
--- a/core_lib/src/tool/buckettool.cpp
+++ b/core_lib/src/tool/buckettool.cpp
@@ -18,6 +18,7 @@ GNU General Public License for more details.
 
 #include <QPixmap>
 #include <QPainter>
+#include <QPointer>
 #include <QtMath>
 #include <QSettings>
 #include "pointerevent.h"
@@ -47,6 +48,7 @@ void BucketTool::loadSettings()
 {
     mPropertyEnabled[TOLERANCE] = true;
     mPropertyEnabled[WIDTH] = true;
+    mPropertyEnabled[FILL_MODE] = true;
 
     QSettings settings(PENCIL2D, PENCIL2D);
 
@@ -54,6 +56,7 @@ void BucketTool::loadSettings()
     properties.feather = 10;
     properties.stabilizerLevel = StabilizationLevel::NONE;
     properties.useAA = DISABLED;
+    properties.fillMode = settings.value("fillMode", 0).toInt();
     properties.tolerance = settings.value("tolerance", 32.0).toDouble();
 }
 
@@ -61,6 +64,7 @@ void BucketTool::resetToDefault()
 {
     setWidth(4.0);
     setTolerance(32.0);
+    setFillMode(0);
 }
 
 QCursor BucketTool::cursor()
@@ -79,6 +83,17 @@ QCursor BucketTool::cursor()
     }
 }
 
+void BucketTool::setTolerance(const int tolerance)
+{
+    // Set current property
+    properties.tolerance = tolerance;
+
+    // Update settings
+    QSettings settings(PENCIL2D, PENCIL2D);
+    settings.setValue("tolerance", tolerance);
+    settings.sync();
+}
+
 /**
  * @brief BrushTool::setWidth
  * @param width
@@ -95,14 +110,14 @@ void BucketTool::setWidth(const qreal width)
     settings.sync();
 }
 
-void BucketTool::setTolerance(const int tolerance)
+void BucketTool::setFillMode(int mode)
 {
     // Set current property
-    properties.tolerance = tolerance;
+    properties.fillMode = mode;
 
     // Update settings
     QSettings settings(PENCIL2D, PENCIL2D);
-    settings.setValue("tolerance", tolerance);
+    settings.setValue("fillMode", mode);
     settings.sync();
 }
 
@@ -169,11 +184,68 @@ void BucketTool::paintBitmap(Layer* layer)
 
     QPoint point = QPoint(qFloor(getLastPoint().x()), qFloor(getLastPoint().y()));
     QRect cameraRect = mScribbleArea->getCameraRect().toRect();
-    BitmapImage::floodFill(targetImage,
-                           cameraRect,
-                           point,
-                           qPremultiply(mEditor->color()->frontColor().rgba()),
-                           properties.tolerance);
+
+    QRgb fillColor = qPremultiply(mEditor->color()->frontColor().rgba());
+    QRgb origColor = fillColor;
+    if (properties.fillMode == 0)
+    {
+        if (qAlpha(fillColor) == 0)
+        {
+            // Filling in overlay mode with a fully transparent color has no
+            // effect, so we can skip it in this case
+            return;
+        }
+    }
+    else if (properties.fillMode == 1)
+    {
+        // Pass a fully opaque version of the new color to floodFill
+        // This is required so we can fully mask out the existing data before
+        // writing the new color.
+        QColor tempColor;
+        tempColor.setRgba(fillColor);
+        tempColor.setAlphaF(1);
+        fillColor = tempColor.rgba();
+    }
+
+    std::unique_ptr<BitmapImage> fillImage(
+                BitmapImage::floodFill(targetImage,
+                                       cameraRect,
+                                       point,
+                                       fillColor,
+                                       properties.tolerance));
+
+    if (fillImage == nullptr)
+    {
+        // Nothing was filled for whatever reason
+        return;
+    }
+
+    switch(properties.fillMode)
+    {
+    default:
+    case 0: // Overlay mode
+        // Write fill image on top of target image
+        targetImage->paste(fillImage.get());
+        break;
+    case 1: // Replace mode
+        if (qAlpha(origColor) == 0xFF)
+        {
+            // When the new color is fully opaque, replace mode
+            // behaves exactly like overlay mode, and origColor == fillColor
+            targetImage->paste(fillImage.get());
+        }
+        else
+        {
+            // Clearly all pixels in the to-be-filled region from the target image
+            targetImage->paste(fillImage.get(), QPainter::CompositionMode_DestinationOut);
+            // Reduce the opacity of the fill to match the new color
+            BitmapImage properColor(targetImage->bounds(), QColor::fromRgba(origColor));
+            properColor.paste(fillImage.get(), QPainter::CompositionMode_DestinationIn);
+            // Write reduced-opacity fill image on top of target image
+            targetImage->paste(&properColor);
+        }
+        break;
+    }
 
     mScribbleArea->setModified(layerNumber, mEditor->currentFrame());
 }
diff --git a/core_lib/src/tool/buckettool.h b/core_lib/src/tool/buckettool.h
index 900e7e44cb..b8331cff8c 100644
--- a/core_lib/src/tool/buckettool.h
+++ b/core_lib/src/tool/buckettool.h
@@ -41,6 +41,7 @@ class BucketTool : public StrokeTool
 
     void setTolerance(const int tolerance) override;
     void setWidth(const qreal width) override;
+    void setFillMode(int mode) override;
 
     void paintBitmap(Layer* layer);
     void paintVector(Layer* layer);
diff --git a/core_lib/src/util/pencildef.h b/core_lib/src/util/pencildef.h
index 9f01776709..6c75527d65 100644
--- a/core_lib/src/util/pencildef.h
+++ b/core_lib/src/util/pencildef.h
@@ -55,6 +55,7 @@ enum ToolPropertyType
     USEFEATHER,
     VECTORMERGE,
     ANTI_ALIASING,
+    FILL_MODE,
     STABILIZATION,
     TOLERANCE,
     FILLCONTOUR