diff --git a/src/s/irix5-0.h b/src/s/irix5-0.h
index 1799e34562d..477f85756d4 100644
--- a/src/s/irix5-0.h
+++ b/src/s/irix5-0.h
@@ -123,3 +123,7 @@ char *_getpty();
 #ifdef __GNUC__
 #define C_DEBUG_SWITCH
 #endif
+
+/* Prevent the variable ospeed from being defined by -lcurses
+   because it defines it with too few bytes.  */
+#define ospeed ospeed_