diff --git a/Misc/NEWS.d/next/Build/2026-07-19-12-16-31.gh-issue-154070.f5da07.rst b/Misc/NEWS.d/next/Build/2026-07-19-12-16-31.gh-issue-154070.f5da07.rst
new file mode 100644
index 00000000000000..31c6fd3ece3532
--- /dev/null
+++ b/Misc/NEWS.d/next/Build/2026-07-19-12-16-31.gh-issue-154070.f5da07.rst
@@ -0,0 +1,4 @@
+Build the :mod:`curses` module against a wide-character capable ncurses
+even when it is not named ``ncursesw`` -- for example the pkgsrc ncurses on
+NetBSD and illumos, or the system ncurses on macOS.  Such a library
+previously produced a narrow build.
diff --git a/configure b/configure
index 08b493311a3f92..3a884cc3ff771a 100755
--- a/configure
+++ b/configure
@@ -30910,10 +30910,19 @@ fi
 
 PANEL_CFLAGS=$(echo $PANEL_CFLAGS | sed 's/-D_XOPEN_SOURCE=600//g')
 
-if test "x$with_curses" = xcurses
-then :
+case $with_curses in #(
+  ncursesw|no) :
+     ;; #(
+  *) :
 
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking whether curses supports wide characters" >&5
+  save_CFLAGS=$CFLAGS
+save_CPPFLAGS=$CPPFLAGS
+save_LDFLAGS=$LDFLAGS
+save_LIBS=$LIBS
+
+
+            as_fn_append CPPFLAGS " $CURSES_CFLAGS"
+    { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking whether curses supports wide characters" >&5
 printf %s "checking whether curses supports wide characters... " >&6; }
 if test ${ac_cv_curses_wide+y}
 then :
@@ -30941,9 +30950,9 @@ int
 main (void)
 {
 
-        cchar_t wcval;
-        setcchar(&wcval, L"x", A_NORMAL, 0, NULL);
-        add_wch(&wcval);
+          cchar_t wcval;
+          setcchar(&wcval, L"x", A_NORMAL, 0, NULL);
+          add_wch(&wcval);
 
   ;
   return 0;
@@ -30962,13 +30971,20 @@ esac
 fi
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_curses_wide" >&5
 printf "%s\n" "$ac_cv_curses_wide" >&6; }
+
+CFLAGS=$save_CFLAGS
+CPPFLAGS=$save_CPPFLAGS
+LDFLAGS=$save_LDFLAGS
+LIBS=$save_LIBS
+
+
       if test "x$ac_cv_curses_wide" = xyes
 then :
   printf "%s\n" "#define HAVE_NCURSESW 1" >>confdefs.h
 
 fi
-
-fi
+ ;;
+esac
 
 # On Solaris, term.h requires curses.h
 ac_fn_c_check_header_compile "$LINENO" "term.h" "ac_cv_header_term_h" "
diff --git a/configure.ac b/configure.ac
index f40db5bc82e24a..2f0ea566565423 100644
--- a/configure.ac
+++ b/configure.ac
@@ -7248,22 +7248,27 @@ AS_VAR_IF([ac_sys_system], [Darwin], [
 dnl pyconfig.h defines _XOPEN_SOURCE=700
 PANEL_CFLAGS=$(echo $PANEL_CFLAGS | sed 's/-D_XOPEN_SOURCE=600//g')
 
-dnl Native curses ("curses") may be wide-character capable (e.g. on NetBSD)
-dnl even though it is not ncursesw.  Probe for the wide API; if present, build
-dnl the module against it like ncursesw by defining HAVE_NCURSESW.  ncursesw
-dnl already defines HAVE_NCURSESW, and ncurses must stay narrow, so only the
-dnl native backend is probed here.
-AS_VAR_IF([with_curses], [curses], [
-  AC_CACHE_CHECK([whether curses supports wide characters],
-    [ac_cv_curses_wide],
-    [AC_LINK_IFELSE(
-      [AC_LANG_PROGRAM([_CURSES_INCLUDES], [[
-        cchar_t wcval;
-        setcchar(&wcval, L"x", A_NORMAL, 0, NULL);
-        add_wch(&wcval);
-      ]])],
-      [ac_cv_curses_wide=yes],
-      [ac_cv_curses_wide=no])])
+dnl A curses that is not named "ncursesw" can still be wide-character capable:
+dnl the system curses of NetBSD, or an ncurses built with --enable-widec that
+dnl keeps the plain name (pkgsrc, macOS).  Probe for the wide API and, if
+dnl present, build the module wide by defining HAVE_NCURSESW.  The "ncursesw"
+dnl backend already defines it, so only the other backends are probed.
+AS_CASE([$with_curses], [ncursesw|no], [], [
+  WITH_SAVE_ENV([
+    dnl Use the adjusted CURSES_CFLAGS (e.g. macOS's -D_XOPEN_SOURCE_EXTENDED)
+    dnl so the wide-character declarations are visible to the probe.
+    AS_VAR_APPEND([CPPFLAGS], [" $CURSES_CFLAGS"])
+    AC_CACHE_CHECK([whether curses supports wide characters],
+      [ac_cv_curses_wide],
+      [AC_LINK_IFELSE(
+        [AC_LANG_PROGRAM([_CURSES_INCLUDES], [[
+          cchar_t wcval;
+          setcchar(&wcval, L"x", A_NORMAL, 0, NULL);
+          add_wch(&wcval);
+        ]])],
+        [ac_cv_curses_wide=yes],
+        [ac_cv_curses_wide=no])])
+  ])
   dnl HAVE_NCURSESW marks the wide (cchar_t) curses API; its template comes
   dnl from the ncursesw pkg-config check above, so no description here.
   AS_VAR_IF([ac_cv_curses_wide], [yes], [AC_DEFINE([HAVE_NCURSESW], [1])])