diff --git a/configure b/configure
index 8ad9cd545..464300c18 100755
--- a/configure
+++ b/configure
@@ -3199,7 +3199,7 @@ else
 #include </usr/include/unistd.h>
 EOF
 if (eval "$ac_cpp conftest.$ac_ext") 2>&5 |
-  egrep "void[ ][ ]*usleep" >/dev/null 2>&1; then
+  egrep "void[ 	]+usleep" >/dev/null 2>&1; then
   rm -rf conftest*
   guile_cv_func_usleep_return_type=void
 else
diff --git a/configure.in b/configure.in
index b6489e9cc..9a4327ebd 100644
--- a/configure.in
+++ b/configure.in
@@ -136,7 +136,7 @@ GUILE_FUNC_DECLARED(usleep, unistd.h)
 ### On some systems usleep has no return value.  If it does have one,
 ### we'd like to return it; otherwise, we'll fake it.
 AC_CACHE_CHECK([return type of usleep], guile_cv_func_usleep_return_type,
-  [AC_EGREP_HEADER(changequote(<, >)<void[ ][ ]*usleep>changequote([, ]),
+  [AC_EGREP_HEADER(changequote(<, >)<void[ 	]+usleep>changequote([, ]),
                    /usr/include/unistd.h,
 		   [guile_cv_func_usleep_return_type=void],
 		   [guile_cv_func_usleep_return_type=int])])