diff --git a/Source/kwsys/ProcessUNIX.c b/Source/kwsys/ProcessUNIX.c
index e4b4219ae..afd9cd823 100644
--- a/Source/kwsys/ProcessUNIX.c
+++ b/Source/kwsys/ProcessUNIX.c
@@ -242,6 +242,14 @@ kwsysProcess* kwsysProcess_New(void)
   /* Share stdin with the parent process by default.  */
   cp->PipeSharedSTDIN = 1;
 
+  /* No native pipes by default.  */
+  cp->PipeNativeSTDIN[0] = -1;
+  cp->PipeNativeSTDIN[1] = -1;
+  cp->PipeNativeSTDOUT[0] = -1;
+  cp->PipeNativeSTDOUT[1] = -1;
+  cp->PipeNativeSTDERR[0] = -1;
+  cp->PipeNativeSTDERR[1] = -1;
+
   /* Set initial status.  */
   cp->State = kwsysProcess_State_Starting;