--- libjpeg-turbo/rdjpgcom.c
+++ libjpeg-turbo/rdjpgcom.c
@@ -227,10 +228,11 @@ process_COM (int raw)
   unsigned int length;
   int ch;
   int lastch = 0;
+  const char *prev_locale;
 
   /* Bill Allombert: set locale properly for isprint */
 #ifdef HAVE_LOCALE_H
-  setlocale(LC_CTYPE, "");
+  prev_locale = setlocale(LC_CTYPE, "");
 #endif
 
   /* Get the marker parameter length count */
@@ -268,7 +270,8 @@ process_COM (int raw)
 
   /* Bill Allombert: revert to C locale */
 #ifdef HAVE_LOCALE_H
-  setlocale(LC_CTYPE, "C");
+  if (prev_locale)
+    setlocale(LC_CTYPE, "C");
 #endif
 }