diff --git a/Auxiliary/Grammars/kranc2.peg b/Auxiliary/Grammars/kranc2.peg
index e078f7e9..a98aaf7e 100644
--- a/Auxiliary/Grammars/kranc2.peg
+++ b/Auxiliary/Grammars/kranc2.peg
@@ -4,7 +4,7 @@ end = ([ \t]+|#.*)*\r*\n
 name = [A-Za-z][A-Za-z0-9]*
 uname = [A-Za-z][A-Za-z0-9_]*
 indices = ([_^]({index_symbol}|\({index_expr}(,{index_expr})*\))+)*
-index_symbol = [a-zA-Z]'*
+index_symbol = [a-zA-Z]'*|[0-9]
 index_expr = {index_symbol}([+-]{int}|)
 tensor = {name}{indices}
 dtensor = D[a-z0-9]*{indices}? {tensor}