# Same counter for different tcolorbox theorems

I have two different types of tcbtheorems: theorem and lemma, defined as below.

\newtcbtheorem[number within=section]{theorem}{Theorem}{some config options}{thm}
\newtcbtheorem[number within=section]{lemma}{Lemma}{some config options}{lem}


If I, somewhere in my document, have

\begin{theorem}{}{}
theorem
\end{theorem}

\begin{lemma}{}{}
lemma
\end{lemma}


It produces "Theorem 1.1" and "Lemma 1.1," whereas I'd like it to produce "Theorem 1.1" and then "Lemma 1.2."

• Please provide us with a complete compilable example, which starts with \documentclass and ends with \end{document}. (And if I am not mistaken this has not too much to do with tcolorbox, rather you have to use a shared counter for your theorems.) – marmot Dec 24 '18 at 2:52

Just add the option use counter from=theorem when defining the new lemma \newtcbtheorem

\documentclass{article}
\usepackage{tcolorbox}
\tcbuselibrary{theorems}
\newtcbtheorem[number within=section]{theorem}{Theorem}{}{thm}
\newtcbtheorem[number within=section,
use counter from=theorem % <----------------
]{lemma}{Lemma}{}{lem}

\begin{document}
\section{title section}
\begin{theorem}{}{}
theorem
\end{theorem}

\begin{lemma}{}{}
lemma
\end{lemma}
\end{document}