diff --git a/src/main/objc/SBJson4StreamWriter.m b/src/main/objc/SBJson4StreamWriter.m
index 1954a55e..843a2795 100644
--- a/src/main/objc/SBJson4StreamWriter.m
+++ b/src/main/objc/SBJson4StreamWriter.m
@@ -268,6 +268,7 @@ - (BOOL)writeValue:(id)o {
 		case 92: return "\\\\";
 		default:
 			[NSException raise:@"Illegal escape char" format:@"-->%c<-- is not a legal escape character", c];
+			return NULL;
 	}
 }