diff --git a/docs/imgtool.md b/docs/imgtool.md
index 9d50e672..b4dc3b55 100644
--- a/docs/imgtool.md
+++ b/docs/imgtool.md
@@ -61,7 +61,7 @@ primary slot and adds a header and trailer that the bootloader is expecting:
     Options:
       -k, --key filename
       --public-key-format [hash|full]
-      --align [1|2|4|8]             [required]
+      --align [1|2|4|8|16|32]       Alignment used by swap update modes.
       -v, --version TEXT            [required]
       -s, --security-counter TEXT   Specify the value of security counter. Use
                                     the `auto` keyword to automatically generate
diff --git a/scripts/imgtool/main.py b/scripts/imgtool/main.py
index a38abe7d..9dd033c4 100755
--- a/scripts/imgtool/main.py
+++ b/scripts/imgtool/main.py
@@ -377,7 +377,8 @@ class BasedIntParamType(click.ParamType):
               'keyword to automatically generate it from the image version.')
 @click.option('-v', '--version', callback=validate_version,  required=True)
 @click.option('--align', type=click.Choice(['1', '2', '4', '8', '16', '32']),
-              required=False)
+              required=False,
+              help='Alignment used by swap update modes.')
 @click.option('--max-align', type=click.Choice(['8', '16', '32']),
               required=False,
               help='Maximum flash alignment. Set if flash alignment of the '