diff --git a/fastdtw/fastdtw.py b/fastdtw/fastdtw.py
index f010d3a..22648e4 100644
--- a/fastdtw/fastdtw.py
+++ b/fastdtw/fastdtw.py
@@ -62,6 +62,9 @@ def __norm(p):
 
 
 def __fastdtw(x, y, radius, dist):
+    if not np.issubdtype(x.dtype, np.floating) or not np.issubdtype(y.dtype, np.floating):
+        return dtw(x, y, dist=dist)
+    
     min_time_size = radius + 2
 
     if len(x) < min_time_size or len(y) < min_time_size:
@@ -76,8 +79,8 @@ def __fastdtw(x, y, radius, dist):
 
 
 def __prep_inputs(x, y, dist):
-    x = np.asanyarray(x, dtype='float')
-    y = np.asanyarray(y, dtype='float')
+    x = np.asanyarray(x, dtype='str' if isinstance(y[0], str) else 'float')
+    y = np.asanyarray(y, dtype='str' if isinstance(y[0], str) else 'float')
 
     if x.ndim == y.ndim > 1 and x.shape[1] != y.shape[1]:
         raise ValueError('second dimension of x and y must be the same')