diff --git a/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/formatter/CCodeFormatter.java b/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/formatter/CCodeFormatter.java
index 30d936d5669..b385455878e 100644
--- a/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/formatter/CCodeFormatter.java
+++ b/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/formatter/CCodeFormatter.java
@@ -165,6 +165,9 @@ public class CCodeFormatter extends CodeFormatter {
 				} catch (CoreException e) {
 					throw new AbortFormatting(e);
 				}
+				if (ast == null) {
+					throw new AbortFormatting("AST is null");  //$NON-NLS-1$
+				}
 				formatRegions(source, regions, edits, ast);
 			} finally {
 				index.releaseReadLock();