diff --git a/toolchains/arduino/org.eclipse.cdt.arduino.ui/src/org/eclipse/cdt/arduino/ui/internal/downloads/ArduinoDownloadsManager.java b/toolchains/arduino/org.eclipse.cdt.arduino.ui/src/org/eclipse/cdt/arduino/ui/internal/downloads/ArduinoDownloadsManager.java
index 1cdcd34408b..c1bb94e8249 100644
--- a/toolchains/arduino/org.eclipse.cdt.arduino.ui/src/org/eclipse/cdt/arduino/ui/internal/downloads/ArduinoDownloadsManager.java
+++ b/toolchains/arduino/org.eclipse.cdt.arduino.ui/src/org/eclipse/cdt/arduino/ui/internal/downloads/ArduinoDownloadsManager.java
@@ -7,8 +7,13 @@
  *******************************************************************************/
 package org.eclipse.cdt.arduino.ui.internal.downloads;
 
+import java.io.File;
+import java.io.IOException;
+
+import org.eclipse.cdt.arduino.core.internal.ArduinoPreferences;
 import org.eclipse.cdt.arduino.ui.internal.Activator;
 import org.eclipse.jface.dialogs.IDialogConstants;
+import org.eclipse.jface.dialogs.MessageDialog;
 import org.eclipse.jface.wizard.Wizard;
 import org.eclipse.jface.wizard.WizardDialog;
 import org.eclipse.jface.wizard.WizardPage;
@@ -21,6 +26,7 @@ import org.eclipse.swt.events.SelectionAdapter;
 import org.eclipse.swt.events.SelectionEvent;
 import org.eclipse.swt.widgets.Button;
 import org.eclipse.swt.widgets.Composite;
+import org.eclipse.swt.widgets.Shell;
 
 public class ArduinoDownloadsManager extends WizardDialog {
 
@@ -91,4 +97,26 @@ public class ArduinoDownloadsManager extends WizardDialog {
 		finishButton.moveBelow(null);
 	}
 
+	static boolean checkLicense(Shell shell) {
+		File acceptedFile = ArduinoPreferences.getArduinoHome().resolve(".accepted").toFile(); //$NON-NLS-1$
+		if (!acceptedFile.exists()) {
+			String message = "Do you accept the licenses for the platforms and libraries you are downloading?";
+			MessageDialog dialog = new MessageDialog(shell, "Arduino Licensing", null, message,
+					MessageDialog.QUESTION, new String[] { "Yes", "No" }, 0);
+			int rc = dialog.open();
+			if (rc == 0) {
+				try {
+					acceptedFile.createNewFile();
+				} catch (IOException e) {
+					Activator.log(e);
+				}
+				return true;
+			} else {
+				return false;
+			}
+		} else {
+			return true;
+		}
+	}
+
 }
diff --git a/toolchains/arduino/org.eclipse.cdt.arduino.ui/src/org/eclipse/cdt/arduino/ui/internal/downloads/LibrariesTabControl.java b/toolchains/arduino/org.eclipse.cdt.arduino.ui/src/org/eclipse/cdt/arduino/ui/internal/downloads/LibrariesTabControl.java
index bb15b3f8811..8a39fb26534 100644
--- a/toolchains/arduino/org.eclipse.cdt.arduino.ui/src/org/eclipse/cdt/arduino/ui/internal/downloads/LibrariesTabControl.java
+++ b/toolchains/arduino/org.eclipse.cdt.arduino.ui/src/org/eclipse/cdt/arduino/ui/internal/downloads/LibrariesTabControl.java
@@ -263,14 +263,16 @@ public class LibrariesTabControl extends Composite {
 			SelectLibrariesDialog selectDialog = new SelectLibrariesDialog(getShell());
 			selectDialog.setLibraries(availableLibraries);
 			if (selectDialog.open() == Window.OK) {
-				Collection<ArduinoLibrary> selectedLibraries = selectDialog.getChecked();
-				container.run(true, true, monitor -> {
-					try {
-						manager.installLibraries(selectedLibraries, monitor);
-					} catch (CoreException e) {
-						Activator.log(e);
-					}
-				});
+				if (ArduinoDownloadsManager.checkLicense(getShell())) {
+					Collection<ArduinoLibrary> selectedLibraries = selectDialog.getChecked();
+					container.run(true, true, monitor -> {
+						try {
+							manager.installLibraries(selectedLibraries, monitor);
+						} catch (CoreException e) {
+							Activator.log(e);
+						}
+					});
+				}
 			}
 			populateTable();
 		} catch (InterruptedException | InvocationTargetException e) {
diff --git a/toolchains/arduino/org.eclipse.cdt.arduino.ui/src/org/eclipse/cdt/arduino/ui/internal/downloads/PlatformsTabControl.java b/toolchains/arduino/org.eclipse.cdt.arduino.ui/src/org/eclipse/cdt/arduino/ui/internal/downloads/PlatformsTabControl.java
index 31e06837f52..2a35036066f 100644
--- a/toolchains/arduino/org.eclipse.cdt.arduino.ui/src/org/eclipse/cdt/arduino/ui/internal/downloads/PlatformsTabControl.java
+++ b/toolchains/arduino/org.eclipse.cdt.arduino.ui/src/org/eclipse/cdt/arduino/ui/internal/downloads/PlatformsTabControl.java
@@ -257,14 +257,16 @@ public class PlatformsTabControl extends Composite {
 			SelectPlatformsDialog selectDialog = new SelectPlatformsDialog(getShell());
 			selectDialog.setPlatforms(availablePlatforms);
 			if (selectDialog.open() == Window.OK) {
-				Collection<ArduinoPlatform> selectedPlatforms = selectDialog.getSelectedPlatforms();
-				container.run(true, true, monitor -> {
-					try {
-						manager.installPlatforms(selectedPlatforms, monitor);
-					} catch (CoreException e) {
-						Activator.log(e);
-					}
-				});
+				if (ArduinoDownloadsManager.checkLicense(getShell())) {
+					Collection<ArduinoPlatform> selectedPlatforms = selectDialog.getSelectedPlatforms();
+					container.run(true, true, monitor -> {
+						try {
+							manager.installPlatforms(selectedPlatforms, monitor);
+						} catch (CoreException e) {
+							Activator.log(e);
+						}
+					});
+				}
 			}
 			populateTable();
 		} catch (InterruptedException | InvocationTargetException e) {