diff --git a/.gitignore b/.gitignore
index fdfc86f9..532cd277 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,5 @@
 .*.swp
+*~
 
 # intermediate files:
 
diff --git a/configure.ac b/configure.ac
index c99d67ce..0a7e6665 100644
--- a/configure.ac
+++ b/configure.ac
@@ -24,6 +24,7 @@ dnl library checks.
 dnl ================================================================
 
 AC_CHECK_HEADERS([stddef.h])   dnl C89
+AC_CHECK_FUNCS([iswblank])     dnl C99
 
 AC_TYPE_UINT8_T
 AC_TYPE_UINT32_T
diff --git a/tests/printcdata.c b/tests/printcdata.c
index 09eaf1cd..6992bb94 100644
--- a/tests/printcdata.c
+++ b/tests/printcdata.c
@@ -17,6 +17,7 @@
  * along with ucd-tools.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include "config.h"
 #include "ucd/ucd.h"
 
 #include <locale.h>
@@ -25,6 +26,13 @@
 #include <wchar.h>
 #include <wctype.h>
 
+#ifndef HAVE_ISWBLANK
+static int iswblank(wint_t c)
+{
+	return iswspace(c) && !(c >= 0x0A && c <= 0x0D);
+}
+#endif
+
 void fput_utf8c(FILE *out, codepoint_t c)
 {
 	if (c < 0x80)