diff --git a/build/org.eclipse.cdt.managedbuilder.core.tests/tests/org/eclipse/cdt/managedbuilder/language/settings/providers/tests/GCCBuiltinSpecsDetectorTest.java b/build/org.eclipse.cdt.managedbuilder.core.tests/tests/org/eclipse/cdt/managedbuilder/language/settings/providers/tests/GCCBuiltinSpecsDetectorTest.java
index d8f3eab1379..6caaee1d3ae 100644
--- a/build/org.eclipse.cdt.managedbuilder.core.tests/tests/org/eclipse/cdt/managedbuilder/language/settings/providers/tests/GCCBuiltinSpecsDetectorTest.java
+++ b/build/org.eclipse.cdt.managedbuilder.core.tests/tests/org/eclipse/cdt/managedbuilder/language/settings/providers/tests/GCCBuiltinSpecsDetectorTest.java
@@ -401,6 +401,36 @@ public class GCCBuiltinSpecsDetectorTest extends BaseTestCase {
 		assertEquals(1, entries.size());
 	}
 
+
+	/**
+	 * Test parsing of include directives included multiple times.
+	 */
+	public void testGCCBuiltinSpecsDetector_Includes_Duplicates() throws Exception {
+		// Create model project and folders to test
+		String projectName = getName();
+		IProject project = ResourceHelper.createCDTProject(projectName);
+		IPath tmpPath = ResourceHelper.createTemporaryFolder();
+		ResourceHelper.createFolder(project, "/usr/include");
+		String loc = tmpPath.toString();
+
+		MockGCCBuiltinSpecsDetector detector = new MockGCCBuiltinSpecsDetector();
+		detector.startup(null, null);
+		detector.startupForLanguage(null);
+
+		detector.processLine("#include <...> search starts here:");
+		detector.processLine(" "+loc+"/usr/include");
+		detector.processLine(" "+loc+"/usr/include");
+		detector.processLine(" "+loc+"/usr/include/");
+		detector.processLine(" "+loc+"/usr/include/../include");
+		detector.processLine("End of search list.");
+		detector.shutdownForLanguage();
+		detector.shutdown();
+
+		List<ICLanguageSettingEntry> entries = detector.getSettingEntries(null, null, null);
+		int index = 0;
+		assertEquals(new CIncludePathEntry(loc+"/usr/include", ICSettingEntry.BUILTIN | ICSettingEntry.READONLY), entries.get(index++));
+		assertEquals(index, entries.size());
+	}
 	/**
 	 * Test parsing of include directives for Cygwin for global provider.
 	 */
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 09aa575fba3..1b6377ee9ae 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
@@ -700,7 +700,11 @@ public abstract class AbstractBuiltinSpecsDetector extends AbstractLanguageSetti
 		// Built-in specs detectors collect entries not per line but for the whole output
 		// so collect them to save later when output finishes
 		if (entries != null) {
-			detectedSettingEntries.addAll(entries);
+			for (ICLanguageSettingEntry entry : entries) {
+				if (!detectedSettingEntries.contains(entry)) {
+					detectedSettingEntries.add(entry);
+				}
+			}
 		}
 	}