[Tex/LaTex] No indentation after theorem environment with amsthm

Question

I use the amsthm package and dont want lines which start right after the theorem environment to be indented. I consulted the manual of the package and it said to define a new theorem style. I expected the following MWE to accomplish this task.

\documentclass[12pt,a4paper]{scrreprt}

\usepackage{amsthm}
\newtheoremstyle{abcd}% name
  {}%      Space above, empty = `usual value'
  {}%      Space below
  {\itshape}% Body font
  {}%         Indent amount (empty = no indent, \parindent = para indent)
  {\bfseries}% Thm head font
  {.}%        Punctuation after thm head
  {.5em}% Space after thm head: \newline = linebreak
  {}%         Thm head spec
\theoremstyle{abcd}

\newtheorem{defn}{Definition}
\begin{document}
\begin{defn}
Some defintion
\end{defn}
This sentence shouldn't be indented.
\end{document}

However, I end up with this

That is what I would expect (obtained using a noindent right after the theorem environment ends)