diff --git a/mantle/platform/api/aws/images.go b/mantle/platform/api/aws/images.go
index 95566584ed..eb2bf22081 100644
--- a/mantle/platform/api/aws/images.go
+++ b/mantle/platform/api/aws/images.go
@@ -344,11 +344,14 @@ func (a *API) CreateHVMImage(snapshotID string, diskSizeGiB uint, name string, d
 	if !set {
 		imdsSupport = "v2.0"
 	}
+	bootmode, set = os.LookupEnv("MANTLE_AWS_BOOT_MODE_x86_64")
 
 	switch architecture {
 	case "amd64", "x86_64":
 		awsArch = ec2.ArchitectureTypeX8664
-		bootmode = "uefi-preferred"
+		if !set {
+			bootmode = "uefi-preferred"
+		}
 	case "arm64", "aarch64":
 		awsArch = ec2.ArchitectureTypeArm64
 		bootmode = "uefi"
diff --git a/src/cosalib/aws.py b/src/cosalib/aws.py
index 284e0737d6..529e310011 100644
--- a/src/cosalib/aws.py
+++ b/src/cosalib/aws.py
@@ -119,7 +119,7 @@ def aws_run_ore(build, args):
     )
     os.environ["MANTLE_AWS_IMDS_SUPPORT"] = image_yaml['aws-imds-support']
     os.environ["MANTLE_AWS_VOLUME_TYPE"] = image_yaml['aws-volume-type']
-    os.environ["aws_boot_mode"] = image_yaml['aws-boot-mode']
+    os.environ["MANTLE_AWS_BOOT_MODE_x86_64"] = image_yaml['aws-boot-mode-x86-64']
 
     # First add the ore command to run before any options
     ore_args = ['ore', 'aws', 'upload']
diff --git a/src/image-default.yaml b/src/image-default.yaml
index 854b558cf6..675bc0cb0d 100644
--- a/src/image-default.yaml
+++ b/src/image-default.yaml
@@ -31,3 +31,4 @@ vmware-secure-boot: true
 # Defaults for AWS
 aws-imds-support: "v2.0"
 aws-volume-type: "gp3"
+aws-boot-mode-x86-64: "uefi-preferred"