diff --git a/src/main/java/org/verapdf/parser/PDFStreamParser.java b/src/main/java/org/verapdf/parser/PDFStreamParser.java
index 06537f2a..2ba6f7a5 100644
--- a/src/main/java/org/verapdf/parser/PDFStreamParser.java
+++ b/src/main/java/org/verapdf/parser/PDFStreamParser.java
@@ -194,7 +194,7 @@ public Object parseNextToken() throws IOException {
 						imageOperator.setImageData(((InlineImageOperator) nextToken).getImageData());
 					} else {
 						throw new IOException("Unexpected token instead of " +
-								"operator in operator parsing: " + nextToken.toString());
+								"operator in operator parsing: " + (nextToken != null ? nextToken.toString() : "null"));
 					}
 				}
 				break;