diff --git a/src/corelib/text/qbytearray.cpp b/src/corelib/text/qbytearray.cpp
index 8151588234..6ae0237d55 100644
--- a/src/corelib/text/qbytearray.cpp
+++ b/src/corelib/text/qbytearray.cpp
@@ -558,6 +558,12 @@ static QByteArray dataIsNull(ZLibOp op)
     return zlibError(op, "Data is null");
 }
 
+Q_DECL_COLD_FUNCTION
+static QByteArray lengthIsNegative(ZLibOp op)
+{
+    return zlibError(op, "Input length is negative");
+}
+
 Q_DECL_COLD_FUNCTION
 static QByteArray tooMuchData(ZLibOp op)
 {
@@ -579,6 +585,9 @@ QByteArray qCompress(const uchar* data, qsizetype nbytes, int compressionLevel)
     if (!data)
         return dataIsNull(ZLibOp::Compression);
 
+    if (nbytes < 0)
+        return lengthIsNegative(ZLibOp::Compression);
+
     if (compressionLevel < -1 || compressionLevel > 9)
         compressionLevel = -1;
 
@@ -657,6 +666,9 @@ QByteArray qUncompress(const uchar* data, qsizetype nbytes)
     if (!data)
         return dataIsNull(ZLibOp::Decompression);
 
+    if (nbytes < 0)
+        return lengthIsNegative(ZLibOp::Decompression);
+
     constexpr qsizetype HeaderSize = sizeof(CompressSizeHint_t);
     if (nbytes < HeaderSize)
         return invalidCompressedData();