diff --git a/tests/auto/corelib/io/largefile/tst_largefile.cpp b/tests/auto/corelib/io/largefile/tst_largefile.cpp
index d05c5bca9fb..088f3e96f2e 100644
--- a/tests/auto/corelib/io/largefile/tst_largefile.cpp
+++ b/tests/auto/corelib/io/largefile/tst_largefile.cpp
@@ -62,12 +62,17 @@ public:
         , fd_(-1)
         , stream_(0)
     {
-    #if defined(QT_LARGEFILE_SUPPORT) && !defined(Q_OS_MAC)
+    #if defined(QT_LARGEFILE_SUPPORT) && !defined(Q_OS_MAC) && !defined(Q_OS_QNX)
         maxSizeBits = 36; // 64 GiB
     #elif defined(Q_OS_MAC)
         // HFS+ does not support sparse files, so we limit file size for the test
         // on Mac OS.
         maxSizeBits = 24; // 16 MiB
+    #elif defined(Q_OS_QNX)
+        // Many of the filesystems that QNX supports use a 32-bit format.
+        // This means that files are limited to 2 GB − 1 bytes.
+        // Limit max size to 256MB
+        maxSizeBits = 28; // 256 MiB
     #else
         maxSizeBits = 24; // 16 MiB
     #endif