diff --git a/src/buildHTML.js b/src/buildHTML.js
index dccf161..534166d 100644
--- a/src/buildHTML.js
+++ b/src/buildHTML.js
@@ -83,7 +83,7 @@ var buildExpression = function(expression, options, isRealGroup) {
             i--;
         } else if (spaces) {
             if (groups[i] instanceof domTree.symbolNode) {
-                groups[i] = makeSpan(groups[i].classes, [groups[i]]);
+                groups[i] = makeSpan([].concat(groups[i].classes), [groups[i]]);
             }
             buildCommon.prependChildren(groups[i], spaces);
             spaces = null;
diff --git a/test/screenshotter/images/StyleSpacing-chrome.png b/test/screenshotter/images/StyleSpacing-chrome.png
new file mode 100644
index 0000000..dad5e8c
Binary files /dev/null and b/test/screenshotter/images/StyleSpacing-chrome.png differ
diff --git a/test/screenshotter/images/StyleSpacing-firefox.png b/test/screenshotter/images/StyleSpacing-firefox.png
new file mode 100644
index 0000000..6599401
Binary files /dev/null and b/test/screenshotter/images/StyleSpacing-firefox.png differ
diff --git a/test/screenshotter/ss_data.yaml b/test/screenshotter/ss_data.yaml
index a37a692..d5e9135 100644
--- a/test/screenshotter/ss_data.yaml
+++ b/test/screenshotter/ss_data.yaml
@@ -117,6 +117,7 @@ Sqrt: |
 SqrtRoot: |
     1+\sqrt[3]{2}+\sqrt[1923^234]{2^{2^{2^{2^{2^{2^{2^{2^{2^{2^{2^2}}}}}}}}}}}
 StackRel: a \stackrel{?}{=} b \stackrel{\text{def}}{=} c
+StyleSpacing: \scriptstyle ab\;cd
 StyleSwitching: a\cdot b\scriptstyle a\cdot ba\textstyle\cdot ba\scriptstyle\cdot b
 SupSubCharacterBox: a_2f_2{f}_2{aa}_2{af}_2\mathbf{y}_Ay_A
 SupSubHorizSpacing: |