diff --git a/theme/boost/templates/core_form/element-button-inline.mustache b/theme/boost/templates/core_form/element-button-inline.mustache
index fff81f93191..173cbbd5467 100644
--- a/theme/boost/templates/core_form/element-button-inline.mustache
+++ b/theme/boost/templates/core_form/element-button-inline.mustache
@@ -2,7 +2,7 @@
     {{$element}}
         {{^element.frozen}}
             <button
-                class="btn btn-secondary"
+                class="btn btn-secondary {{{element.extraclasses}}}"
                 name="{{element.name}}"
                 id="{{element.id}}"
                 type="button"
diff --git a/theme/boost/templates/core_form/element-submit-inline.mustache b/theme/boost/templates/core_form/element-submit-inline.mustache
index 71158500d98..bd2663cd893 100644
--- a/theme/boost/templates/core_form/element-submit-inline.mustache
+++ b/theme/boost/templates/core_form/element-submit-inline.mustache
@@ -5,6 +5,7 @@
                 class="btn
                     {{^element.secondary}}btn-primary{{/element.secondary}}
                     {{#element.secondary}}btn-secondary{{/element.secondary}}
+                    {{{element.extraclasses}}}
                     {{#error}} btn-danger {{/error}}"
                 name="{{element.name}}"
                 id="{{element.id}}"
diff --git a/theme/boost/templates/core_form/element-template-inline.mustache b/theme/boost/templates/core_form/element-template-inline.mustache
index 98ec035ae8f..18b261dae47 100644
--- a/theme/boost/templates/core_form/element-template-inline.mustache
+++ b/theme/boost/templates/core_form/element-template-inline.mustache
@@ -1,4 +1,4 @@
-<div class="form-group {{#error}}has-danger{{/error}} fitem {{#advanced}}advanced{{/advanced}} {{{element.extraclasses}}}" {{#element.groupname}}data-groupname="{{.}}"{{/element.groupname}}>
+<div class="form-group {{#error}}has-danger{{/error}} fitem {{#advanced}}advanced{{/advanced}}" {{#element.groupname}}data-groupname="{{.}}"{{/element.groupname}}>
     <label class="col-form-label {{#element.hiddenlabel}}sr-only{{/element.hiddenlabel}}" for="{{element.id}}">
         {{{label}}} {{{helpbutton}}}
         {{#required}}<abbr class="initialism text-danger" title="{{#str}}required{{/str}}">{{#pix}}req, core, {{#str}}required{{/str}}{{/pix}}</abbr>{{/required}}