diff --git a/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/formatter/CodeFormatterVisitor.java b/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/formatter/CodeFormatterVisitor.java
index 05c2f61d5b4..2506888c156 100644
--- a/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/formatter/CodeFormatterVisitor.java
+++ b/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/formatter/CodeFormatterVisitor.java
@@ -2483,8 +2483,10 @@ public class CodeFormatterVisitor extends ASTVisitor implements ICPPASTVisitor,
 	 */
 	private void formatList(List<?> elements, ListOptions options, boolean encloseInParen, boolean addEllipsis,
 			Runnable tailFormatter, Runnable prefix) {
-		if (encloseInParen)
-			scribe.printNextToken(options.leftToken, options.fSpaceBeforeOpeningParen);
+		if (encloseInParen) {
+			if (peekNextToken() == options.leftToken)
+				scribe.printNextToken(options.leftToken, options.fSpaceBeforeOpeningParen);
+		}
 
 		final int elementsLength = elements.size();
 		if (encloseInParen) {
diff --git a/core/org.eclipse.cdt.ui.tests/ui/org/eclipse/cdt/ui/tests/text/CodeFormatterTest.java b/core/org.eclipse.cdt.ui.tests/ui/org/eclipse/cdt/ui/tests/text/CodeFormatterTest.java
index f7f52b193ad..c112ca61d88 100644
--- a/core/org.eclipse.cdt.ui.tests/ui/org/eclipse/cdt/ui/tests/text/CodeFormatterTest.java
+++ b/core/org.eclipse.cdt.ui.tests/ui/org/eclipse/cdt/ui/tests/text/CodeFormatterTest.java
@@ -4699,4 +4699,13 @@ public class CodeFormatterTest extends BaseUITestCase {
 	public void testStructuredBindingInSwitchInitStatement() throws Exception {
 		assertFormatterResult();
 	}
+
+	//#define PROTO(X) X
+	//void foo PROTO((char* b));
+
+	//#define PROTO(X) X
+	//void foo PROTO((char* b));
+	public void testMacroInFunctionParameters_Bug550096() throws Exception {
+		assertFormatterResult();
+	}
 }