diff --git a/libexec/pyenv-init b/libexec/pyenv-init
index 3892ec65..6341b655 100755
--- a/libexec/pyenv-init
+++ b/libexec/pyenv-init
@@ -47,7 +47,11 @@ done
 
 # If shell is not provided, detect it.
 if [ -z "$shell" ]; then
-  shell="$(ps -p "$PPID" -o 'args=' 2>/dev/null || true)"
+  if shell=$(tr '\0' ' ' 2>/dev/null </proc/"$PPID"/cmdline);then
+  	  :
+  else
+  	  shell=$(ps p "$PPID" -o 'args=' 2>/dev/null || true)
+  fi
   shell="${shell%% *}"
   shell="${shell##-}"
   shell="${shell:-$SHELL}"