diff --git a/less/forms.less b/less/forms.less
index 3138c2c518..0017dfd41d 100644
--- a/less/forms.less
+++ b/less/forms.less
@@ -198,7 +198,7 @@ input[type="search"] {
 // horizontal forms, use the predefined grid classes.
 
 .form-group {
-  margin-bottom: 15px;
+  margin-bottom: @form-group-margin-bottom;
 }
 
 
diff --git a/less/variables.less b/less/variables.less
index 002be6afb2..a647983eb1 100644
--- a/less/variables.less
+++ b/less/variables.less
@@ -207,6 +207,9 @@
 //** Small `.form-control` height
 @input-height-small:             (floor(@font-size-small * @line-height-small) + (@padding-small-vertical * 2) + 2);
 
+//** `.form-group` margin
+@form-group-margin-bottom:       15px;
+
 @legend-color:                   @gray-dark;
 @legend-border-color:            #e5e5e5;