diff --git a/src/main/java/org/verapdf/parser/PDFStreamParser.java b/src/main/java/org/verapdf/parser/PDFStreamParser.java
index 06537f2a..6865fd01 100644
--- a/src/main/java/org/verapdf/parser/PDFStreamParser.java
+++ b/src/main/java/org/verapdf/parser/PDFStreamParser.java
@@ -193,8 +193,9 @@ public Object parseNextToken() throws IOException {
 					if (nextToken instanceof InlineImageOperator) {
 						imageOperator.setImageData(((InlineImageOperator) nextToken).getImageData());
 					} else {
-						throw new IOException("Unexpected token instead of " +
-								"operator in operator parsing: " + nextToken.toString());
+						throw new IOException(nextToken != null
+                                ? ("Unexpected token instead of operator in operator parsing: " + nextToken.toString())
+                                : "Null token instead of operator in operator parsing");
 					}
 				}
 				break;