diff --git a/composer.json b/composer.json
index 924614f6f2..0bb62a6141 100644
--- a/composer.json
+++ b/composer.json
@@ -64,6 +64,7 @@
 		"ext-zlib": "TYPO3 uses zlib for amongst others output compression and un/packing t3x extension files"
 	},
 	"conflict": {
+		"guzzlehttp/guzzle": ">= 6.5.0",
 		"symfony/cache": "< 2.8.50 >= 2.8.0 || < 3.4.26 >= 3.4.0 || < 4.1.12 >= 4.1.0 || < 4.2.7 >= 4.2.0",
 		"symfony/finder": "2.7.44 || 2.8.37 || 3.4.7 || 4.0.7",
 		"typo3/cms": "*",