diff --git a/src/complete.c b/src/complete.c
index 2642908..974e4ab 100644
--- a/src/complete.c
+++ b/src/complete.c
@@ -23,7 +23,7 @@
 
 #define MAX_TOTAL_MATCHES (256 << sizeof(char *))
 
-#ifdef NEED_STRDUP
+#ifndef HAVE_STRDUP
 /* Return an allocated copy of a string. */
 char *strdup(const char *p)
 {
diff --git a/src/editline.h b/src/editline.h
index 22c0923..dbd4a3f 100644
--- a/src/editline.h
+++ b/src/editline.h
@@ -93,7 +93,7 @@ extern int	strlen(const char *s);
 extern int	strncmp(const char *s1, const char *s2, size_t n);
 #endif/* !HAVE_STDLIB */
 
-#ifdef NEED_STRDUP
+#ifndef HAVE_STRDUP
 extern char	*strdup(const char *s);
 #endif