diff --git a/ChangeLog b/ChangeLog
index 3ef9570e10..259f788f36 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,11 @@
 2020-09-25  Paul Eggert  <eggert@cs.ucla.edu>
 
+	regex-tests: fix possible Turkish false-alarm
+	* modules/regex-tests (Depends-on): Add wctype-h.
+	* tests/test-regex.c: Include wctype.h.
+	(main): Check that ‘i’ uppercases to ‘İ’ in Turkish,
+	as the Turkish regex test assumes this.
+
 	regex-tests: fix test and add debug output
 	Perhaps this will fix the recent grep test failure reported at:
 	https://buildfarm.opencsw.org/buildbot/builders/ggrep-solaris10-sparc/builds/199
diff --git a/modules/regex-tests b/modules/regex-tests
index 711632aa06..4b14f4724c 100644
--- a/modules/regex-tests
+++ b/modules/regex-tests
@@ -5,6 +5,7 @@ tests/macros.h
 Depends-on:
 gettext-h
 localcharset
+wctype-h
 
 configure.ac:
 
diff --git a/tests/test-regex.c b/tests/test-regex.c
index 96def52f59..a54f643d83 100644
--- a/tests/test-regex.c
+++ b/tests/test-regex.c
@@ -24,6 +24,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <wctype.h>
 #if HAVE_DECL_ALARM
 # include <unistd.h>
 # include <signal.h>
@@ -141,7 +142,8 @@ main (void)
         return 1;
     }
 
-  if (setlocale (LC_ALL, "tr_TR.UTF-8") && really_utf8 ())
+  if (setlocale (LC_ALL, "tr_TR.UTF-8") && really_utf8 ()
+      && towupper (L'i') == 0x0130 /* U+0130; see below.  */)
     {
       re_set_syntax (RE_SYNTAX_GREP | RE_ICASE);
       memset (&regex, 0, sizeof regex);