diff --git a/Source/cmCTest.cxx b/Source/cmCTest.cxx
index 0274e2769..50a269233 100644
--- a/Source/cmCTest.cxx
+++ b/Source/cmCTest.cxx
@@ -2363,9 +2363,7 @@ int cmCTest::RunMakeCommand(const char* command, std::string* output,
     std::cout << "   Each . represents " << tick_len << " bytes of output" << std::endl;
     std::cout << "    " << std::flush;
     }
-  while(cmsysProcess_WaitForData(cp, (cmsysProcess_Pipe_STDOUT |
-                                      cmsysProcess_Pipe_STDERR),
-                                 &data, &length, 0))
+  while(cmsysProcess_WaitForData(cp, &data, &length, 0))
     {
     if ( output )
       {
@@ -2454,9 +2452,7 @@ int cmCTest::RunTest(std::vector<const char*> argv, std::string* output, int *re
   
   char* data;
   int length;
-  while(cmsysProcess_WaitForData(cp, (cmsysProcess_Pipe_STDOUT |
-                                      cmsysProcess_Pipe_STDERR),
-                                 &data, &length, 0))
+  while(cmsysProcess_WaitForData(cp, &data, &length, 0))
     {
     if ( output )
       {
diff --git a/Source/cmSystemTools.cxx b/Source/cmSystemTools.cxx
index 341348d3b..8d1640d5c 100644
--- a/Source/cmSystemTools.cxx
+++ b/Source/cmSystemTools.cxx
@@ -403,9 +403,7 @@ bool cmSystemTools::RunSingleCommand(
   std::vector<char> tempOutput;
   char* data;
   int length;
-  while(cmsysProcess_WaitForData(cp, (cmsysProcess_Pipe_STDOUT |
-                                      cmsysProcess_Pipe_STDERR),
-                                 &data, &length, 0))
+  while(cmsysProcess_WaitForData(cp, &data, &length, 0))
     {
     if ( output )
       {
diff --git a/Source/kwsys/Process.h.in b/Source/kwsys/Process.h.in
index 16ccddd29..0583c0c34 100644
--- a/Source/kwsys/Process.h.in
+++ b/Source/kwsys/Process.h.in
@@ -213,13 +213,9 @@ kwsysEXPORT const char* kwsysProcess_GetErrorString(kwsysProcess* cp);
 kwsysEXPORT void kwsysProcess_Execute(kwsysProcess* cp);
 
 /**
- * Block until data are available on a requested pipe, a timeout
- * expires, or the child process terminates.  Arguments are as
- * follows:
+ * Block until data are available on a pipe, a timeout expires, or the
+ * child process terminates.  Arguments are as follows:
  *
- *  pipes   = Flags for the child output pipes of interest to the caller.
- *            Possible values are Pipe_STDOUT and Pipe_STDERR.  Multiple
- *            pipes may be specified by using the bitwise OR operator '|'.
  *  data    = If data are read, the pointer to which this points is
  *            set to point to the data.
  *  length  = If data are read, the integer to which this points is
@@ -241,9 +237,8 @@ kwsysEXPORT void kwsysProcess_Execute(kwsysProcess* cp);
  *                  call.  Time elapsed has been subtracted from timeout
  *                  argument.
  */
-kwsysEXPORT int kwsysProcess_WaitForData(kwsysProcess* cp, int pipes,
-                                         char** data, int* length,
-                                         double* timeout);
+kwsysEXPORT int kwsysProcess_WaitForData(kwsysProcess* cp, char** data,
+                                         int* length, double* timeout);
 enum kwsysProcess_Pipes_e
 {
   kwsysProcess_Pipe_STDOUT=1,
diff --git a/Source/kwsys/ProcessUNIX.c b/Source/kwsys/ProcessUNIX.c
index 5efd0b969..7e8c61785 100644
--- a/Source/kwsys/ProcessUNIX.c
+++ b/Source/kwsys/ProcessUNIX.c
@@ -486,8 +486,8 @@ void kwsysProcess_Execute(kwsysProcess* cp)
 }
 
 /*--------------------------------------------------------------------------*/
-int kwsysProcess_WaitForData(kwsysProcess* cp, int pipes, char** data,
-                             int* length, double* userTimeout)
+int kwsysProcess_WaitForData(kwsysProcess* cp, char** data, int* length,
+                             double* userTimeout)
 {
   int i;
   int max = -1;
@@ -537,9 +537,9 @@ int kwsysProcess_WaitForData(kwsysProcess* cp, int pipes, char** data,
             {
             /* This is data on the special termination pipe.  Ignore it.  */
             }
-          else if(pipes & (1 << i))
+          else if(data && length)
             {
-            /* Caller wants this data.  Report it.  */
+            /* Report this data.  */
             *data = cp->PipeBuffer;
             *length = n;
             pipeId = (1 << i);
@@ -687,7 +687,7 @@ int kwsysProcess_WaitForExit(kwsysProcess* cp, double* userTimeout)
     }
 
   /* Wait for all the pipes to close.  Ignore all data.  */
-  while((pipe = kwsysProcess_WaitForData(cp, 0, 0, 0, userTimeout)) > 0)
+  while((pipe = kwsysProcess_WaitForData(cp, 0, 0, userTimeout)) > 0)
     {
     if(pipe == kwsysProcess_Pipe_Timeout)
       {
diff --git a/Source/kwsys/ProcessWin32.c b/Source/kwsys/ProcessWin32.c
index 7317cf7eb..fd4ddd04e 100644
--- a/Source/kwsys/ProcessWin32.c
+++ b/Source/kwsys/ProcessWin32.c
@@ -921,7 +921,7 @@ void kwsysProcess_Execute(kwsysProcess* cp)
 
 /*--------------------------------------------------------------------------*/
 
-int kwsysProcess_WaitForData(kwsysProcess* cp, int pipes, char** data, int* length,
+int kwsysProcess_WaitForData(kwsysProcess* cp, char** data, int* length,
                              double* userTimeout)
 {
   kwsysProcessTime userStartTime;
@@ -997,18 +997,14 @@ int kwsysProcess_WaitForData(kwsysProcess* cp, int pipes, char** data, int* leng
         /* The pipe closed.  */
         --cp->PipesLeft;
         }
-      else if(pipes & (1 << cp->CurrentIndex))
+      else if(data && length)
         {
-        /* Caller wants this data.  Report it.  */
+        /* Report this data.  */
         *data = cp->Pipe[cp->CurrentIndex].DataBuffer;
         *length = cp->Pipe[cp->CurrentIndex].DataLength;
         pipeId = (1 << cp->CurrentIndex);
         done = 1;
         }
-      else
-        {
-        /* Caller does not care about this pipe.  Ignore the data.  */
-        }
       }
     else
       {
@@ -1074,7 +1070,7 @@ int kwsysProcess_WaitForExit(kwsysProcess* cp, double* userTimeout)
     }
 
   /* Wait for the process to terminate.  Ignore all data.  */
-  while((pipe = kwsysProcess_WaitForData(cp, 0, 0, 0, userTimeout)) > 0)
+  while((pipe = kwsysProcess_WaitForData(cp, 0, 0, userTimeout)) > 0)
     {
     if(pipe == kwsysProcess_Pipe_Timeout)
       {
diff --git a/Source/kwsys/test1.cxx b/Source/kwsys/test1.cxx
index 7dd61a494..84c3f8d85 100644
--- a/Source/kwsys/test1.cxx
+++ b/Source/kwsys/test1.cxx
@@ -11,9 +11,7 @@ int main()
   kwsysProcess_Execute(kp);
   char* data = 0;
   int length = 0;
-  while(kwsysProcess_WaitForData(kp, (kwsysProcess_Pipe_STDOUT |
-                                      kwsysProcess_Pipe_STDERR),
-                                 &data, &length, 0))
+  while(kwsysProcess_WaitForData(kp, &data, &length, 0))
     {
     kwsys_std::cout.write(data, length);
     }
diff --git a/Source/kwsys/testProcess.c b/Source/kwsys/testProcess.c
index c569528d5..1b4ea7480 100644
--- a/Source/kwsys/testProcess.c
+++ b/Source/kwsys/testProcess.c
@@ -66,9 +66,7 @@ int runChild(const char* cmd[], int state, int exception, int value)
   kwsysProcess_SetTimeout(kp, 3);
   kwsysProcess_Execute(kp);
   
-  while(kwsysProcess_WaitForData(kp, (kwsysProcess_Pipe_STDOUT |
-                                      kwsysProcess_Pipe_STDERR),
-                                 &data, &length, 0))
+  while(kwsysProcess_WaitForData(kp, &data, &length, 0))
     {
     fwrite(data, 1, length, stdout);
     fflush(stdout);