diff --git a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/scanner/PreprocessorBugsTests.java b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/scanner/PreprocessorBugsTests.java
index 65c9db08c35..a4b21c1ff18 100644
--- a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/scanner/PreprocessorBugsTests.java
+++ b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/scanner/PreprocessorBugsTests.java
@@ -84,5 +84,12 @@ public class PreprocessorBugsTests extends PreprocessorTestsBase {
 		validateEOF();
 		validateProblemCount(0);
 	}
-
+	
+	// __CDT_PARSER__
+	public void testPredefinedCDTMacro_Bug173848() throws Exception {
+		initializeScanner();
+		validateInteger("1");
+		validateEOF();
+		validateProblemCount(0);
+	}
 }
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/CPreprocessor.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/CPreprocessor.java
index c1ade5cb948..3254d427ca1 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/CPreprocessor.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/CPreprocessor.java
@@ -76,6 +76,7 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
 
 
     // standard built-ins
+    private static final ObjectStyleMacro __CDT_PARSER__= new ObjectStyleMacro("__CDT_PARSER__".toCharArray(), ONE);   //$NON-NLS-1$
     private static final ObjectStyleMacro __cplusplus = new ObjectStyleMacro("__cplusplus".toCharArray(), ONE);   //$NON-NLS-1$
     private static final ObjectStyleMacro __STDC__ = new ObjectStyleMacro("__STDC__".toCharArray(), ONE);  //$NON-NLS-1$
     private static final ObjectStyleMacro __STDC_HOSTED__ = new ObjectStyleMacro("__STDC_HOSTED_".toCharArray(), ONE);  //$NON-NLS-1$
@@ -259,6 +260,7 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
 
     private void setupMacroDictionary(IScannerExtensionConfiguration config, IScannerInfo info, ParserLanguage lang) {
     	// built in macros
+    	fMacroDictionary.put(__CDT_PARSER__.getNameCharArray(), __CDT_PARSER__);
         fMacroDictionary.put(__STDC__.getNameCharArray(), __STDC__);
         fMacroDictionary.put(__FILE__.getNameCharArray(), __FILE__);
         fMacroDictionary.put(__DATE__.getNameCharArray(), __DATE__);