diff --git a/config.h.in b/config.h.in
index 5ed8b0c85..6ee7f616f 100644
--- a/config.h.in
+++ b/config.h.in
@@ -129,6 +129,10 @@
    don't. */
 #undef HAVE_DECL_GETRESUID
 
+/* Define to 1 if you have the declaration of `getusershell', and to 0 if you
+   don't. */
+#undef HAVE_DECL_GETUSERSHELL
+
 /* Define to 1 if you have the declaration of `h_errno', and to 0 if you
    don't. */
 #undef HAVE_DECL_H_ERRNO
diff --git a/configure b/configure
index cad9ee52e..db0f72ff0 100755
--- a/configure
+++ b/configure
@@ -19940,6 +19940,17 @@ if test "x$ac_cv_func_getusershell" = xyes
 then :
   printf "%s\n" "#define HAVE_GETUSERSHELL 1" >>confdefs.h
 
+    # Older Solaris has getusershell() et al but does not declare it.
+    ac_fn_check_decl "$LINENO" "getusershell" "ac_cv_have_decl_getusershell" "$ac_includes_default" "$ac_c_undeclared_builtin_options" "CFLAGS"
+if test "x$ac_cv_have_decl_getusershell" = xyes
+then :
+  ac_have_decl=1
+else $as_nop
+  ac_have_decl=0
+fi
+printf "%s\n" "#define HAVE_DECL_GETUSERSHELL $ac_have_decl" >>confdefs.h
+
+
 else $as_nop
 
     case " $LIBOBJS " in
diff --git a/configure.ac b/configure.ac
index e9e22e0fa..d8701d30e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2600,7 +2600,10 @@ AC_CHECK_FUNCS([getdelim], [
     SUDO_APPEND_COMPAT_EXP(sudo_getdelim)
     COMPAT_TEST_PROGS="${COMPAT_TEST_PROGS}${COMPAT_TEST_PROGS+ }getdelim_test"
 ])
-AC_CHECK_FUNCS([getusershell], [], [
+AC_CHECK_FUNCS([getusershell], [
+    # Older Solaris has getusershell() et al but does not declare it.
+    AC_CHECK_DECLS([getusershell])
+], [
     AC_LIBOBJ(getusershell)
     SUDO_APPEND_COMPAT_EXP(sudo_getusershell)
 ])
diff --git a/include/sudo_compat.h b/include/sudo_compat.h
index 99a62ded2..05e479974 100644
--- a/include/sudo_compat.h
+++ b/include/sudo_compat.h
@@ -441,6 +441,11 @@ sudo_dso_public void sudo_setusershell(void);
 sudo_dso_public void sudo_endusershell(void);
 # undef endusershell
 # define endusershell() sudo_endusershell()
+#elif HAVE_DECL_GETUSERSHELL == 0
+/* Older Solaris has getusershell() et al but does not declare it. */
+char *getusershell(void);
+void setusershell(void);
+void endusershell(void);
 #endif /* HAVE_GETUSERSHELL */
 #ifndef HAVE_UTIMENSAT
 sudo_dso_public int sudo_utimensat(int fd, const char *file, const struct timespec *times, int flag);