diff --git a/core/math/parser/parser.factor b/core/math/parser/parser.factor
index 0a637c2eab..3fd62e69a0 100644
--- a/core/math/parser/parser.factor
+++ b/core/math/parser/parser.factor
@@ -50,7 +50,9 @@ SYMBOL: radix
 SYMBOL: negative?
 
 : string>natural ( seq radix -- n/f )
-    [ [ digit> ] dip (digits>integer) ] each-digit ; inline
+    over empty? [ 2drop f ] [
+        [ [ digit> ] dip (digits>integer) ] each-digit
+    ] if ; inline
 
 : sign ( -- str ) negative? get "-" "+" ? ;