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 82eeac7506a..08d8fed97fc 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
@@ -275,4 +275,27 @@ public class PreprocessorBugsTests extends PreprocessorTestsBase {
 		validateEOF();
 		validateProblemCount(0); 
 	}
+	
+	// #error // 
+	// #warning // 
+	// #pragma  // not marked as problem
+	// #define //
+	// #include //
+	// #undef //
+	// #if //
+	// #endif
+	// #ifdef //
+	// #endif
+	// #ifndef //
+	// #endif
+	// #if 0
+	// #elif //
+	// #endif
+	// a
+	public void testMissingArgument_Bug303969() throws Exception {
+		initializeScanner();
+		validateIdentifier("a");
+		validateEOF();
+		validateProblemCount(9); 
+	}
 }
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 9fcefe8490c..6b5df9223a0 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
@@ -1110,6 +1110,10 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
     	case IPreprocessorDirective.ppError:
     		int condOffset= lexer.nextToken().getOffset();
     		condEndOffset= lexer.consumeLine(ORIGIN_PREPROCESSOR_DIRECTIVE);
+    		// Missing argument
+			if (condEndOffset < condOffset) {
+				condOffset= condEndOffset;
+			}
     		if (fCurrentContext.getCodeState() == CodeState.eActive) {
     			int endOffset= lexer.currentToken().getEndOffset();
     			final char[] warning= lexer.getInputChars(condOffset, condEndOffset);
@@ -1123,6 +1127,10 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
     	case IPreprocessorDirective.ppPragma:
     		condOffset= lexer.nextToken().getOffset();
     		condEndOffset= lexer.consumeLine(ORIGIN_PREPROCESSOR_DIRECTIVE);
+    		// Missing argument
+			if (condEndOffset < condOffset) {
+				condOffset= condEndOffset;
+			}
     		if (fCurrentContext.getCodeState() == CodeState.eActive) {
     			int endOffset= lexer.currentToken().getEndOffset();
     			fLocationMap.encounterPoundPragma(startOffset, condOffset, condEndOffset, endOffset);
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/Lexer.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/Lexer.java
index 51ef841a4db..5ad61e2a86f 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/Lexer.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/Lexer.java
@@ -15,6 +15,7 @@ import org.eclipse.cdt.core.parser.IGCCToken;
 import org.eclipse.cdt.core.parser.IProblem;
 import org.eclipse.cdt.core.parser.IToken;
 import org.eclipse.cdt.core.parser.OffsetLimitReachedException;
+import org.eclipse.cdt.core.parser.util.CharArrayUtils;
 
 /**
  * In short this class converts line endings (to '\n') and trigraphs 
@@ -1139,6 +1140,9 @@ final public class Lexer implements ITokenSequence {
 	 */
 	public char[] getInputChars(int offset, int endOffset) {
 		final int length= endOffset-offset;
+		if (length <= 0) {
+			return CharArrayUtils.EMPTY;
+		}
 		final char[] result= new char[length];
 		fInput.arraycopy(offset, result, 0, length);
 		return result;