diff --git a/frontend_tests/node_tests/compose_ui.js b/frontend_tests/node_tests/compose_ui.js
index 4e285d16ca..a3fce18a28 100644
--- a/frontend_tests/node_tests/compose_ui.js
+++ b/frontend_tests/node_tests/compose_ui.js
@@ -57,13 +57,22 @@ function make_textbox(s) {
     assert.equal(textbox.val(), 'abc :smile: :airplane:');
     assert(textbox.focused);
 
-    // Test the current slightly-broken behavior.
     textbox.caret(0);
     textbox.blur();
     compose_ui.smart_insert(textbox, ':octopus:');
-    assert.equal(textbox.insert_text, ':octopus:');
-    assert.equal(textbox.val(), ':octopus:abc :smile: :airplane:');
+    assert.equal(textbox.insert_text, ':octopus: ');
+    assert.equal(textbox.val(), ':octopus: abc :smile: :airplane:');
     assert(textbox.focused);
 
+    textbox.caret(textbox.val().length);
+    textbox.blur();
+    compose_ui.smart_insert(textbox, ':heart:');
+    assert.equal(textbox.insert_text, ' :heart:');
+    assert.equal(textbox.val(), ':octopus: abc :smile: :airplane: :heart:');
+    assert(textbox.focused);
+
+    // Note that we don't have any special logic for strings that are
+    // already surrounded by spaces, since we are usually inserting things
+    // like emojis and file links.
 }());
 
diff --git a/static/js/compose_ui.js b/static/js/compose_ui.js
index 12fdae0d7a..6e72e2d1f0 100644
--- a/static/js/compose_ui.js
+++ b/static/js/compose_ui.js
@@ -13,7 +13,7 @@ exports.smart_insert = function (textarea, syntax) {
 
     var pos = textarea.caret();
     var before_str = textarea.val().slice(0, pos);
-
+    var after_str = textarea.val().slice(pos);
 
     if (pos > 0) {
         if (!is_space(before_str.slice(-1))) {
@@ -21,6 +21,12 @@ exports.smart_insert = function (textarea, syntax) {
         }
     }
 
+    if (after_str.length > 0) {
+        if (!is_space(after_str[0])) {
+            syntax += ' ';
+        }
+    }
+
     textarea.caret(syntax);
     textarea.focus();
 };