diff --git a/arch/x86/kernel/amd_iommu_init.c b/arch/x86/kernel/amd_iommu_init.c
index 595edd2befc66ff8b4eb7aec27ba9d4047716d83..30ae2701b3df1b8976400d5996ed72a4a98baeea 100644
--- a/arch/x86/kernel/amd_iommu_init.c
+++ b/arch/x86/kernel/amd_iommu_init.c
@@ -1215,7 +1215,7 @@ static int __init parse_amd_iommu_options(char *str)
 			amd_iommu_isolate = 1;
 		if (strncmp(str, "share", 5) == 0)
 			amd_iommu_isolate = 0;
-		if (strncmp(str, "fullflush", 11) == 0)
+		if (strncmp(str, "fullflush", 9) == 0)
 			amd_iommu_unmap_flush = true;
 	}