diff --git a/flatlaf-core/src/main/java/com/formdev/flatlaf/icons/FlatInternalFrameCloseIcon.java b/flatlaf-core/src/main/java/com/formdev/flatlaf/icons/FlatInternalFrameCloseIcon.java
new file mode 100644
index 00000000..3471eece
--- /dev/null
+++ b/flatlaf-core/src/main/java/com/formdev/flatlaf/icons/FlatInternalFrameCloseIcon.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright 2019 FormDev Software GmbH
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.formdev.flatlaf.icons;
+
+import java.awt.BasicStroke;
+import java.awt.Component;
+import java.awt.Graphics2D;
+import java.awt.geom.Line2D;
+import java.awt.geom.Path2D;
+import javax.swing.UIManager;
+
+/**
+ * "close" icon for {@link javax.swing.JInternalFrame}.
+ *
+ * @uiDefault InternalFrame.iconColor			Color
+ *
+ * @author Karl Tauber
+ */
+public class FlatInternalFrameCloseIcon
+	extends FlatAbstractIcon
+{
+	public FlatInternalFrameCloseIcon() {
+		super( 16, 16, UIManager.getColor( "InternalFrame.iconColor" ) );
+	}
+
+	@Override
+	protected void paintIcon( Component c, Graphics2D g ) {
+		float mx = 8;
+		float my = 8;
+		float r = 3.25f;
+
+		Path2D path = new Path2D.Float( Path2D.WIND_EVEN_ODD );
+		path.append( new Line2D.Float( mx - r, my - r, mx + r, my + r ), false );
+		path.append( new Line2D.Float( mx - r, my + r, mx + r, my - r ), false );
+		g.setStroke( new BasicStroke( 1f ) );
+		g.draw( path );
+	}
+}
diff --git a/flatlaf-core/src/main/java/com/formdev/flatlaf/icons/FlatInternalFrameIconifyIcon.java b/flatlaf-core/src/main/java/com/formdev/flatlaf/icons/FlatInternalFrameIconifyIcon.java
new file mode 100644
index 00000000..2f59b283
--- /dev/null
+++ b/flatlaf-core/src/main/java/com/formdev/flatlaf/icons/FlatInternalFrameIconifyIcon.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright 2019 FormDev Software GmbH
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.formdev.flatlaf.icons;
+
+import java.awt.Component;
+import java.awt.Graphics2D;
+import javax.swing.UIManager;
+
+/**
+ * "iconify" icon for {@link javax.swing.JInternalFrame}.
+ *
+ * @uiDefault InternalFrame.iconColor			Color
+ *
+ * @author Karl Tauber
+ */
+public class FlatInternalFrameIconifyIcon
+	extends FlatAbstractIcon
+{
+	public FlatInternalFrameIconifyIcon() {
+		super( 16, 16, UIManager.getColor( "InternalFrame.iconColor" ) );
+	}
+
+	@Override
+	protected void paintIcon( Component c, Graphics2D g ) {
+		g.fillRect( 3, 8, 10, 1 );
+	}
+}
diff --git a/flatlaf-core/src/main/java/com/formdev/flatlaf/icons/FlatInternalFrameMaximizeIcon.java b/flatlaf-core/src/main/java/com/formdev/flatlaf/icons/FlatInternalFrameMaximizeIcon.java
new file mode 100644
index 00000000..3439e3de
--- /dev/null
+++ b/flatlaf-core/src/main/java/com/formdev/flatlaf/icons/FlatInternalFrameMaximizeIcon.java
@@ -0,0 +1,42 @@
+/*
+ * Copyright 2019 FormDev Software GmbH
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.formdev.flatlaf.icons;
+
+import java.awt.Component;
+import java.awt.Graphics2D;
+import javax.swing.UIManager;
+import com.formdev.flatlaf.ui.FlatUIUtils;
+
+/**
+ * "maximize" icon for {@link javax.swing.JInternalFrame}.
+ *
+ * @uiDefault InternalFrame.iconColor			Color
+ *
+ * @author Karl Tauber
+ */
+public class FlatInternalFrameMaximizeIcon
+	extends FlatAbstractIcon
+{
+	public FlatInternalFrameMaximizeIcon() {
+		super( 16, 16, UIManager.getColor( "InternalFrame.iconColor" ) );
+	}
+
+	@Override
+	protected void paintIcon( Component c, Graphics2D g ) {
+		g.fill( FlatUIUtils.createRectangle( 3, 3, 10, 10, 1 ) );
+	}
+}
diff --git a/flatlaf-core/src/main/java/com/formdev/flatlaf/icons/FlatInternalFrameMinimizeIcon.java b/flatlaf-core/src/main/java/com/formdev/flatlaf/icons/FlatInternalFrameMinimizeIcon.java
new file mode 100644
index 00000000..d829cfcc
--- /dev/null
+++ b/flatlaf-core/src/main/java/com/formdev/flatlaf/icons/FlatInternalFrameMinimizeIcon.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright 2019 FormDev Software GmbH
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.formdev.flatlaf.icons;
+
+import java.awt.Component;
+import java.awt.Graphics2D;
+import java.awt.geom.Area;
+import java.awt.geom.Path2D;
+import java.awt.geom.Rectangle2D;
+import javax.swing.UIManager;
+import com.formdev.flatlaf.ui.FlatUIUtils;
+
+/**
+ * "minimize" (actually "restore") icon for {@link javax.swing.JInternalFrame}.
+ *
+ * @uiDefault InternalFrame.iconColor			Color
+ *
+ * @author Karl Tauber
+ */
+public class FlatInternalFrameMinimizeIcon
+	extends FlatAbstractIcon
+{
+	public FlatInternalFrameMinimizeIcon() {
+		super( 16, 16, UIManager.getColor( "InternalFrame.iconColor" ) );
+	}
+
+	@Override
+	protected void paintIcon( Component c, Graphics2D g ) {
+		Path2D r1 = FlatUIUtils.createRectangle( 5, 3, 8, 8, 1 );
+		Path2D r2 = FlatUIUtils.createRectangle( 3, 5, 8, 8, 1 );
+
+		Area area = new Area( r1 );
+		area.subtract( new Area( new Rectangle2D.Float( 3, 5, 8, 8 ) ) );
+		g.fill( area );
+
+		g.fill( r2 );
+	}
+}
diff --git a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatUIUtils.java b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatUIUtils.java
index b29d16bc..386cac0a 100644
--- a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatUIUtils.java
+++ b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatUIUtils.java
@@ -278,6 +278,17 @@ public class FlatUIUtils
 		return null;
 	}
 
+	/**
+	 * Creates a not-filled rectangle shape with the given line width.
+	 */
+	public static Path2D createRectangle( float x, float y, float width, float height, float lineWidth ) {
+		Path2D path = new Path2D.Float( Path2D.WIND_EVEN_ODD );
+		path.append( new Rectangle2D.Float( x, y, width, height ), false );
+		path.append( new Rectangle2D.Float( x + lineWidth, y + lineWidth,
+			width - (lineWidth * 2), height - (lineWidth * 2) ), false );
+		return path;
+	}
+
 	/**
 	 * Creates a not-filled rounded rectangle shape and allows specifying the line width and the radius or each corner.
 	 */