diff --git a/build/org.eclipse.cdt.managedbuilder.core.tests/tests/org/eclipse/cdt/managedbuilder/language/settings/providers/tests/BuiltinSpecsDetectorTest.java b/build/org.eclipse.cdt.managedbuilder.core.tests/tests/org/eclipse/cdt/managedbuilder/language/settings/providers/tests/BuiltinSpecsDetectorTest.java
index 68c897fe425..5c3e4e7ab0e 100644
--- a/build/org.eclipse.cdt.managedbuilder.core.tests/tests/org/eclipse/cdt/managedbuilder/language/settings/providers/tests/BuiltinSpecsDetectorTest.java
+++ b/build/org.eclipse.cdt.managedbuilder.core.tests/tests/org/eclipse/cdt/managedbuilder/language/settings/providers/tests/BuiltinSpecsDetectorTest.java
@@ -888,6 +888,41 @@ public class BuiltinSpecsDetectorTest extends BaseTestCase {
 		provider.unregisterListener();
 	}
 
+	/**
+	 * Test running a provider after changing the compiler command.
+	 */
+	public void testAbstractBuiltinSpecsDetector_RerunOnCommandArgsChange() throws Exception {
+		// Create test "compiler"
+		java.io.File compiler = new java.io.File("compiler");
+		compiler.createNewFile();
+		assertTrue(compiler.exists());
+		String compilerPath = compiler.getAbsolutePath();
+
+		// Create provider
+		MockBuiltinSpecsDetectorWithRunCount provider = new MockBuiltinSpecsDetectorWithRunCount();
+		provider.setCommand(compilerPath + " arg1");
+		// register environment listener on workspace
+		provider.registerListener(null);
+		waitForProviderToFinish();
+		assertEquals(1, provider.getExecutedCount());
+
+		// Check that an event doesn't trigger unnecessary rerun
+		provider.handleEvent(null);
+		waitForProviderToFinish();
+		assertEquals(1, provider.getExecutedCount());
+
+		// Change the compiler command
+		provider.setCommand(compilerPath + " arg2");
+
+		// Check that an event triggers rerun after changing the compiler command
+		provider.handleEvent(null);
+		waitForProviderToFinish();
+		assertEquals(2, provider.getExecutedCount());
+
+		// unregister listeners
+		provider.unregisterListener();
+	}
+
 	/**
 	 * Check that entries get grouped by kinds by stock built-in specs detector.
 	 */
diff --git a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/language/settings/providers/AbstractBuiltinSpecsDetector.java b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/language/settings/providers/AbstractBuiltinSpecsDetector.java
index 30d6e4fd1f9..696b57563e4 100644
--- a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/language/settings/providers/AbstractBuiltinSpecsDetector.java
+++ b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/language/settings/providers/AbstractBuiltinSpecsDetector.java
@@ -7,6 +7,7 @@
  *
  * Contributors:
  *     Andrew Gvozdev - initial API and implementation
+ *     Liviu Ionescu - Bug 413678: trigger discovery after command line change
  *******************************************************************************/
 
 package org.eclipse.cdt.managedbuilder.language.settings.providers;
@@ -419,6 +420,10 @@ public abstract class AbstractBuiltinSpecsDetector extends AbstractLanguageSetti
 		for (String languageId : languageIds) {
 			try {
 				String command = resolveCommand(languageId);
+				if (command != null) {
+					envHashNew = 31*envHashNew + command.hashCode();
+				}
+
 				String[] cmdArray = CommandLineUtil.argumentsToArray(command);
 				if (cmdArray != null && cmdArray.length > 0) {
 					IPath location = new Path(cmdArray[0]);