diff --git a/include/ompi_stdint.h b/include/ompi_stdint.h
index 5cace1007e..6fc7e14226 100644
--- a/include/ompi_stdint.h
+++ b/include/ompi_stdint.h
@@ -34,6 +34,7 @@
 /*
  * Include what we can and define what is missing.
  */
+#include <limits.h>
 
 #ifdef HAVE_INTTYPES_H
 #include <inttypes.h>
@@ -182,6 +183,18 @@ typedef unsigned long long uintptr_t;
 
 #endif
 
+/* fix up some constants that may be missing */
+#ifndef SIZE_MAX
+#if SIZEOF_VOID_P == SIZEOF_INT
+#define SIZE_MAX UINT_MAX
+#elif SIZEOF_VOID_P == SIZEOF_LONG
+#define SIZE_MAX ULONG_MAX
+#else
+#error Failed to find value for SIZE_MAX
+#endif
+
+#endif /* ifndef SIZE_MAX */
+
 #endif /* HAVE_STDINT_H */
 
 #endif /* OMPI_STDINT_H */
diff --git a/orte/mca/gpr/base/gpr_base_open.c b/orte/mca/gpr/base/gpr_base_open.c
index 91422f3ebd..db5159bde4 100644
--- a/orte/mca/gpr/base/gpr_base_open.c
+++ b/orte/mca/gpr/base/gpr_base_open.c
@@ -17,8 +17,9 @@
  */
 
 #include "orte_config.h"
+
 #include "orte/include/orte_constants.h"
-\
+
 #include "opal/util/output.h"
 #include "opal/util/trace.h"
 
diff --git a/orte/mca/oob/base/base.h b/orte/mca/oob/base/base.h
index 8d03c113ad..bb5937dec8 100644
--- a/orte/mca/oob/base/base.h
+++ b/orte/mca/oob/base/base.h
@@ -25,6 +25,10 @@
 
 #include "orte_config.h"
 
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+
 #include "dps/dps_types.h"
 #include "mca/mca.h"
 #include "mca/ns/ns_types.h"
diff --git a/orte/mca/oob/base/oob_base_ping.c b/orte/mca/oob/base/oob_base_ping.c
index c356752a87..0cff6b461a 100644
--- a/orte/mca/oob/base/oob_base_ping.c
+++ b/orte/mca/oob/base/oob_base_ping.c
@@ -24,6 +24,9 @@
 #ifdef HAVE_NETINET_IN_H
 #include <netinet/in.h>
 #endif
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
     
 #include "include/constants.h"
 #include "opal/util/argv.h"
diff --git a/orte/mca/oob/oob.h b/orte/mca/oob/oob.h
index 3d62be088f..690cc9305d 100644
--- a/orte/mca/oob/oob.h
+++ b/orte/mca/oob/oob.h
@@ -25,6 +25,10 @@
 
 #include "ompi_config.h"
 
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+
 #include "include/types.h"
 #include "mca/mca.h"
 
diff --git a/orte/mca/rml/rml.h b/orte/mca/rml/rml.h
index 7d7f1b5849..c108d4d647 100644
--- a/orte/mca/rml/rml.h
+++ b/orte/mca/rml/rml.h
@@ -24,6 +24,11 @@
 #define ORTE_RML_H_
 
 #include "orte_config.h"
+
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+
 #include "include/orte_constants.h"
 
 #include "mca/mca.h"