diff --git a/src/main/java/com/hubspot/jinjava/lib/exptest/IsInExpTest.java b/src/main/java/com/hubspot/jinjava/lib/exptest/IsInExpTest.java
index f40d2b37e..0fac8f969 100644
--- a/src/main/java/com/hubspot/jinjava/lib/exptest/IsInExpTest.java
+++ b/src/main/java/com/hubspot/jinjava/lib/exptest/IsInExpTest.java
@@ -36,7 +36,7 @@ public boolean evaluate(Object value, JinjavaInterpreter interpreter, Object...
     if (args == null || args.length == 0) {
       return false;
     }
-    if (!isIterable(args[0])) {
+    if (!(args[0] instanceof CharSequence) && !isIterable(args[0])) {
       throw new InvalidArgumentException(
         interpreter,
         this,
diff --git a/src/test/java/com/hubspot/jinjava/lib/filter/RejectAttrFilterTest.java b/src/test/java/com/hubspot/jinjava/lib/filter/RejectAttrFilterTest.java
index 9d7ed44e7..4a82b93a9 100644
--- a/src/test/java/com/hubspot/jinjava/lib/filter/RejectAttrFilterTest.java
+++ b/src/test/java/com/hubspot/jinjava/lib/filter/RejectAttrFilterTest.java
@@ -75,6 +75,17 @@ public void rejectAttrWithNestedProperty() {
       .isEqualTo("[1, 2]");
   }
 
+  @Test
+  public void rejectAttrWithStringMembershipExp() {
+    assertThat(
+      jinjava.render(
+        "{{ [('action', 'down_single'), ('event_type', 'down_single')] | rejectattr(0, 'in', 'name,event_type') | list }}",
+        new HashMap<String, Object>()
+      )
+    )
+      .isEqualTo("[['action', 'down_single']]");
+  }
+
   public static class User implements PyishSerializable {
 
     private int num;