...you put a backslash before the '@' character(s) in your string literal(s) :)

Background is that when Perl sees something like "foo abc@xyz bar", it attempts to interpolate an array @xyz, and if there is no such array in the program, Perl warns that this interpolation might be unintended...

BTW, with use diagnostics, you would have gotten virtually the same explanation for free:

Possible unintended interpolation of @xyz in string at ...
    (W ambiguous) You said something like `@foo' in a double-quoted st
+ring
    but there was no array @foo in scope at the time. If you wanted a
    literal @foo, then write it as \@foo; otherwise find out what happ
+ened
    to the array you apparently lost track of.
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