diff --git a/superset/connectors/druid/models.py b/superset/connectors/druid/models.py
index ca955a7c8d..4ad6a6f951 100644
--- a/superset/connectors/druid/models.py
+++ b/superset/connectors/druid/models.py
@@ -980,9 +980,9 @@ class DruidDatasource(Model, BaseDatasource):
                 eq = eq[0] if len(eq) > 0 else ''
             if col in self.num_cols:
                 if op in ('in', 'not in'):
-                    eq = [utils.js_string_to_num(v) for v in eq]
+                    eq = [utils.string_to_num(v) for v in eq]
                 else:
-                    eq = utils.js_string_to_num(eq)
+                    eq = utils.string_to_num(eq)
             if op == '==':
                 cond = Dimension(col) == eq
             elif op == '!=':
diff --git a/superset/connectors/sqla/models.py b/superset/connectors/sqla/models.py
index c853b59139..913ee59579 100644
--- a/superset/connectors/sqla/models.py
+++ b/superset/connectors/sqla/models.py
@@ -1,6 +1,7 @@
 from datetime import datetime
 import logging
 import sqlparse
+from past.builtins import basestring
 
 import pandas as pd
 
@@ -467,9 +468,19 @@ class SqlaTable(Model, BaseDatasource):
             col_obj = cols.get(col)
             if col_obj:
                 if op in ('in', 'not in'):
-                    values = [types.strip("'").strip('"') for types in eq]
-                    if col_obj.is_num:
-                        values = [utils.js_string_to_num(s) for s in values]
+                    values = []
+                    for v in eq:
+                        # For backwards compatibility and edge cases
+                        # where a column data type might have changed
+                        if isinstance(v, basestring):
+                            v = v.strip("'").strip('"')
+                            if col_obj.is_num:
+                                v = utils.string_to_num(v)
+
+                        # Removing empty strings and non numeric values
+                        # targeting numeric columns
+                        if v is not None:
+                            values.append(v)
                     cond = col_obj.sqla_col.in_(values)
                     if op == 'not in':
                         cond = ~cond
diff --git a/superset/utils.py b/superset/utils.py
index ec4c18d896..2cfd7a5992 100644
--- a/superset/utils.py
+++ b/superset/utils.py
@@ -128,14 +128,32 @@ class memoized(object):  # noqa
 def js_string_to_python(item):
     return None if item in ('null', 'undefined') else item
 
-def js_string_to_num(item):
-    if item.isdigit():
-        return int(item)
-    s = item
-    try:
-        s = float(item)
-    except ValueError:
+
+def string_to_num(s):
+    """Converts a string to an int/float
+
+    Returns ``None`` if it can't be converted
+
+    >>> string_to_num('5')
+    5
+    >>> string_to_num('5.2')
+    5.2
+    >>> string_to_num(10)
+    10
+    >>> string_to_num(10.1)
+    10.1
+    >>> string_to_num('this is not a string') is None
+    True
+    """
+    if isinstance(s, (int, float)):
         return s
+    if s.isdigit():
+        return int(s)
+    try:
+        return float(s)
+    except ValueError:
+        return None
+
 
 class DimSelector(Having):
     def __init__(self, **args):