diff --git a/src/core/parser.js b/src/core/parser.js
index 92816879e..118c42633 100644
--- a/src/core/parser.js
+++ b/src/core/parser.js
@@ -203,7 +203,12 @@ class Parser {
       } else if (state === 1) {
         state = ch === I ? 2 : 0;
       } else {
-        assert(state === 2, "findDefaultInlineStreamEnd - invalid state.");
+        if (
+          typeof PDFJSDev === "undefined" ||
+          PDFJSDev.test("!PRODUCTION || TESTING")
+        ) {
+          assert(state === 2, "findDefaultInlineStreamEnd - invalid state.");
+        }
         if (ch === SPACE || ch === LF || ch === CR) {
           maybeEIPos = stream.pos;
           // Let's check that the next `n` bytes are ASCII... just to be sure.