diff --git a/src/configure.in b/src/configure.in
index c8c06274f2d23a7c992cdee851c9f9b5d3f2ca2f..b870ebfc765a6754dfcf6a25952a1168ebf3a243 100644
--- a/src/configure.in
+++ b/src/configure.in
@@ -4579,7 +4579,6 @@ AC_CHECK_FUNCS( \
  strcasecmp \
  strnlen \
  strchr \
- strcspn \
  strerror \
  times \
  tzset \
diff --git a/src/port.c b/src/port.c
index ccb00c911ac210364cbf3850ff2e11525ebb254e..9baeb5a50537281a5fac7ee8f9e6d64d1d42a78d 100644
--- a/src/port.c
+++ b/src/port.c
@@ -560,7 +560,7 @@ void own_gethrtime_init()
        p = STRSTR(buf, "\ncpu MHz");
        if (p) {
 	 p += sizeof("\ncpu MHz");
-	 p += STRCSPN(p, "0123456789\n");
+	 p += strcspn(p, "0123456789\n");
 	 if (*p != '\n') {
 	   long long hz = 0;
 
diff --git a/src/port.h b/src/port.h
index 29a2156d9e0235f9253f855fe5d273fb06acdcd7..c472f7684bcba4b9df7dc3c5356065234ecbf762 100644
--- a/src/port.h
+++ b/src/port.h
@@ -155,11 +155,8 @@ void GETTIMEOFDAY(struct timeval *t);
 #define HAVE_STRTOD 1
 #define STRTOD strtod
 
-#ifndef HAVE_STRCSPN
-int STRCSPN(const char *s,const char * set);
-#else
-#  define STRCSPN strcspn
-#endif
+#define HAVE_STRCSPN 1
+#define STRCSPN strcspn
 
 #ifndef HAVE_STRCASECMP
 PMOD_EXPORT int STRCASECMP(const char *a,const char *b);