diff --git a/makejdk-any-platform.1 b/makejdk-any-platform.1
index f52f95f31..8b840d957 100755
--- a/makejdk-any-platform.1
+++ b/makejdk-any-platform.1
@@ -26,6 +26,9 @@ that you are building for further details.
 
 This will start a Docker container and build you the latest Java 8 Temurin
 binary from the source at https://github.com/adoptium/openjdk-jdk8u
+Note that the main argument, in this case jdk8, is compared and enforced
+against an enumeration - jdk8, jdk8u, ... jdk21, jdk21u, ...jdk. Nothing else.
+You can workaround this by \-\-version switch.
 
 Please visit https://www.adoptium.net for further support
 
diff --git a/sbin/common/common.sh b/sbin/common/common.sh
index a2eac67a9..8508ee0dc 100755
--- a/sbin/common/common.sh
+++ b/sbin/common/common.sh
@@ -17,6 +17,17 @@
 function setOpenJdkVersion() {
   local forest_name=$1
 
+  # The argument passed here have actually very strict format of jdk8, jdk8u..., jdk
+  # the build may fail later if this is not honoured.
+  # If your repository has a different name, you can use --version or build from dir/snapshot
+  local forest_name_check=0
+  echo "$forest_name" | grep -q -e "^jdk$" -e "^jdk[0-9]\\{1,3\\}[u]\\{0,1\\}$" || forest_name_check=$?
+  if [ ${forest_name_check} -ne 0 ]; then
+    echo "The mandatory repo argument has a very strict format 'jdk[0-9]{1,3}[u]{0,1}' or just plain 'jdk' for tip. '$forest_name' does not match."
+    echo "This can be worked around by using '--version jdkXYu'. If set (and matching) then the main argument can have any value."
+    exit 1
+  fi
+
   # Derive the openjdk_core_version from the forest name.
   local openjdk_core_version=${forest_name}
   if [[ ${forest_name} == *u ]]; then