diff --git a/IPython/core/interactiveshell.py b/IPython/core/interactiveshell.py
index 6772740..1a73571 100644
--- a/IPython/core/interactiveshell.py
+++ b/IPython/core/interactiveshell.py
@@ -2639,7 +2639,10 @@ class InteractiveShell(SingletonConfigurable):
         """
         cmd = self.var_expand(cmd, depth=1)
         # warn if there is an IPython magic alternative.
-        main_cmd = cmd.split()[0]
+        if cmd == "":
+            main_cmd = ""
+        else:
+            main_cmd = cmd.split()[0]
         has_magic_alternatives = ("pip", "conda", "cd")
 
         if main_cmd in has_magic_alternatives: