diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 6edd023009..260b8ba0be 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -189,13 +189,14 @@ jobs:
 
           images_out="images"
 
-          if echo "$formats" | tr ' ' '\n' | grep -q '^vmware'; then
-            formats=$(echo "$formats" | tr ' ' '\n' | sed '/vmware.*/d')
-            formats+=" vmware vmware_ova vmware_raw"
+          printf -v formats "%s\n" ${formats}
+          if grep -q '^vmware' <<< "${formats}"; then
+              formats=$(grep -v '^vmware' <<< "${formats}")
+              printf -v formats "%s\n" ${formats} vmware vmware_ova vmware_raw
           fi
-          if echo "$formats" | tr ' ' '\n' | grep -q -P '^(ami|aws)'; then
-            formats=$(echo "$formats" | tr ' ' '\n' | sed '/ami.*/d' | sed '/aws/d')
-            formats+=" ami ami_vmdk"
+          if printf "%s\n" $formats | grep -q '^ami\|^aws'; then
+              formats=$(grep -v '^ami\|^aws' <<< "${formats}")
+              printf -v formats "%s\n" ${formats} ami ami_vmdk
           fi
 
           for format in ${formats}; do
diff --git a/ci-automation/vms.sh b/ci-automation/vms.sh
index aa6c6325b9..1f4074dbdb 100644
--- a/ci-automation/vms.sh
+++ b/ci-automation/vms.sh
@@ -80,14 +80,14 @@ function _vm_build_impl() {
     apply_local_patches
 
     # Convert platform names (also used to find the test scripts) to image formats they entail
-    formats="$*"
-    if echo "$formats" | tr ' ' '\n' | grep -q '^vmware'; then
-      formats=$(echo "$formats" | tr ' ' '\n' | sed '/vmware.*/d')
-      formats+=" vmware vmware_ova vmware_raw"
+    printf -v formats "%s\n" ${formats}
+    if grep -q '^vmware' <<< "${formats}"; then
+        formats=$(grep -v '^vmware' <<< "${formats}")
+        printf -v formats "%s\n" ${formats} vmware vmware_ova vmware_raw
     fi
-    if echo "$formats" | tr ' ' '\n' | grep -q -P '^(ami|aws)'; then
-      formats=$(echo "$formats" | tr ' ' '\n' | sed '/ami.*/d' | sed '/aws/d')
-      formats+=" ami ami_vmdk"
+    if printf "%s\n" $formats | grep -q '^ami\|^aws'; then
+        formats=$(grep -v '^ami\|^aws' <<< "${formats}")
+        printf -v formats "%s\n" ${formats} ami ami_vmdk
     fi
 
     source sdk_lib/sdk_container_common.sh