diff --git a/src/interfaces/libpq/fe-connect.c b/src/interfaces/libpq/fe-connect.c
index ec9a9a570a..5e687c1558 100644
--- a/src/interfaces/libpq/fe-connect.c
+++ b/src/interfaces/libpq/fe-connect.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-connect.c,v 1.358 2008/05/16 18:30:53 mha Exp $
+ *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-connect.c,v 1.359 2008/05/29 22:02:44 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1581,7 +1581,8 @@ keep_going:						/* We will come back to here until there is
 					 * needed to hold the whole message; see notes in
 					 * pqParseInput3.
 					 */
-					if (pqCheckInBufferSpace(conn->inCursor + msgLength, conn))
+					if (pqCheckInBufferSpace(conn->inCursor + (size_t) msgLength,
+											 conn))
 						goto error_return;
 					/* We'll come back when there is more data */
 					return PGRES_POLLING_READING;
diff --git a/src/interfaces/libpq/fe-exec.c b/src/interfaces/libpq/fe-exec.c
index e7941dffe0..25ad0e4a1a 100644
--- a/src/interfaces/libpq/fe-exec.c
+++ b/src/interfaces/libpq/fe-exec.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-exec.c,v 1.194 2008/01/01 19:46:00 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-exec.c,v 1.195 2008/05/29 22:02:44 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1685,7 +1685,8 @@ PQputCopyData(PGconn *conn, const char *buffer, int nbytes)
 		{
 			if (pqFlush(conn) < 0)
 				return -1;
-			if (pqCheckOutBufferSpace(conn->outCount + 5 + nbytes, conn))
+			if (pqCheckOutBufferSpace(conn->outCount + 5 + (size_t) nbytes,
+									  conn))
 				return pqIsnonblocking(conn) ? 0 : -1;
 		}
 		/* Send the data (too simple to delegate to fe-protocol files) */
diff --git a/src/interfaces/libpq/fe-misc.c b/src/interfaces/libpq/fe-misc.c
index 3d06386542..33c704b519 100644
--- a/src/interfaces/libpq/fe-misc.c
+++ b/src/interfaces/libpq/fe-misc.c
@@ -23,7 +23,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-misc.c,v 1.133 2008/01/01 19:46:00 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-misc.c,v 1.134 2008/05/29 22:02:44 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -278,12 +278,12 @@ pqPutInt(int value, size_t bytes, PGconn *conn)
  * Returns 0 on success, EOF if failed to enlarge buffer
  */
 int
-pqCheckOutBufferSpace(int bytes_needed, PGconn *conn)
+pqCheckOutBufferSpace(size_t bytes_needed, PGconn *conn)
 {
 	int			newsize = conn->outBufSize;
 	char	   *newbuf;
 
-	if (bytes_needed <= newsize)
+	if (bytes_needed <= (size_t) newsize)
 		return 0;
 
 	/*
@@ -296,9 +296,9 @@ pqCheckOutBufferSpace(int bytes_needed, PGconn *conn)
 	do
 	{
 		newsize *= 2;
-	} while (bytes_needed > newsize && newsize > 0);
+	} while (newsize > 0 && bytes_needed > (size_t) newsize);
 
-	if (bytes_needed <= newsize)
+	if (newsize > 0 && bytes_needed <= (size_t) newsize)
 	{
 		newbuf = realloc(conn->outBuffer, newsize);
 		if (newbuf)
@@ -314,9 +314,9 @@ pqCheckOutBufferSpace(int bytes_needed, PGconn *conn)
 	do
 	{
 		newsize += 8192;
-	} while (bytes_needed > newsize && newsize > 0);
+	} while (newsize > 0 && bytes_needed > (size_t) newsize);
 
-	if (bytes_needed <= newsize)
+	if (newsize > 0 && bytes_needed <= (size_t) newsize)
 	{
 		newbuf = realloc(conn->outBuffer, newsize);
 		if (newbuf)
@@ -341,12 +341,12 @@ pqCheckOutBufferSpace(int bytes_needed, PGconn *conn)
  * Returns 0 on success, EOF if failed to enlarge buffer
  */
 int
-pqCheckInBufferSpace(int bytes_needed, PGconn *conn)
+pqCheckInBufferSpace(size_t bytes_needed, PGconn *conn)
 {
 	int			newsize = conn->inBufSize;
 	char	   *newbuf;
 
-	if (bytes_needed <= newsize)
+	if (bytes_needed <= (size_t) newsize)
 		return 0;
 
 	/*
@@ -359,9 +359,9 @@ pqCheckInBufferSpace(int bytes_needed, PGconn *conn)
 	do
 	{
 		newsize *= 2;
-	} while (bytes_needed > newsize && newsize > 0);
+	} while (newsize > 0 && bytes_needed > (size_t) newsize);
 
-	if (bytes_needed <= newsize)
+	if (newsize > 0 && bytes_needed <= (size_t) newsize)
 	{
 		newbuf = realloc(conn->inBuffer, newsize);
 		if (newbuf)
@@ -377,9 +377,9 @@ pqCheckInBufferSpace(int bytes_needed, PGconn *conn)
 	do
 	{
 		newsize += 8192;
-	} while (bytes_needed > newsize && newsize > 0);
+	} while (newsize > 0 && bytes_needed > (size_t) newsize);
 
-	if (bytes_needed <= newsize)
+	if (newsize > 0 && bytes_needed <= (size_t) newsize)
 	{
 		newbuf = realloc(conn->inBuffer, newsize);
 		if (newbuf)
@@ -572,7 +572,7 @@ pqReadData(PGconn *conn)
 	 */
 	if (conn->inBufSize - conn->inEnd < 8192)
 	{
-		if (pqCheckInBufferSpace(conn->inEnd + 8192, conn))
+		if (pqCheckInBufferSpace(conn->inEnd + (size_t) 8192, conn))
 		{
 			/*
 			 * We don't insist that the enlarge worked, but we need some room
diff --git a/src/interfaces/libpq/fe-protocol3.c b/src/interfaces/libpq/fe-protocol3.c
index 89c0d5018f..66059493bb 100644
--- a/src/interfaces/libpq/fe-protocol3.c
+++ b/src/interfaces/libpq/fe-protocol3.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-protocol3.c,v 1.34 2008/01/17 21:21:50 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-protocol3.c,v 1.35 2008/05/29 22:02:44 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -115,7 +115,8 @@ pqParseInput3(PGconn *conn)
 			 * recovery strategy if we are unable to make the buffer big
 			 * enough.
 			 */
-			if (pqCheckInBufferSpace(conn->inCursor + msgLength, conn))
+			if (pqCheckInBufferSpace(conn->inCursor + (size_t) msgLength,
+									 conn))
 			{
 				/*
 				 * XXX add some better recovery code... plan is to skip over
@@ -1310,7 +1311,8 @@ getCopyDataMessage(PGconn *conn)
 			 * Before returning, enlarge the input buffer if needed to hold
 			 * the whole message.  See notes in parseInput.
 			 */
-			if (pqCheckInBufferSpace(conn->inCursor + msgLength - 4, conn))
+			if (pqCheckInBufferSpace(conn->inCursor + (size_t) msgLength - 4,
+									 conn))
 			{
 				/*
 				 * XXX add some better recovery code... plan is to skip over
@@ -1745,7 +1747,8 @@ pqFunctionCall3(PGconn *conn, Oid fnid,
 			 * Before looping, enlarge the input buffer if needed to hold the
 			 * whole message.  See notes in parseInput.
 			 */
-			if (pqCheckInBufferSpace(conn->inCursor + msgLength, conn))
+			if (pqCheckInBufferSpace(conn->inCursor + (size_t) msgLength,
+									 conn))
 			{
 				/*
 				 * XXX add some better recovery code... plan is to skip over
diff --git a/src/interfaces/libpq/libpq-int.h b/src/interfaces/libpq/libpq-int.h
index 89b3747350..fd94952f18 100644
--- a/src/interfaces/libpq/libpq-int.h
+++ b/src/interfaces/libpq/libpq-int.h
@@ -12,7 +12,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/interfaces/libpq/libpq-int.h,v 1.130 2008/05/16 18:30:53 mha Exp $
+ * $PostgreSQL: pgsql/src/interfaces/libpq/libpq-int.h,v 1.131 2008/05/29 22:02:44 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -511,8 +511,8 @@ extern PGresult *pqFunctionCall3(PGconn *conn, Oid fnid,
   * Get, EOF merely means the buffer is exhausted, not that there is
   * necessarily any error.
   */
-extern int	pqCheckOutBufferSpace(int bytes_needed, PGconn *conn);
-extern int	pqCheckInBufferSpace(int bytes_needed, PGconn *conn);
+extern int	pqCheckOutBufferSpace(size_t bytes_needed, PGconn *conn);
+extern int	pqCheckInBufferSpace(size_t bytes_needed, PGconn *conn);
 extern int	pqGetc(char *result, PGconn *conn);
 extern int	pqPutc(char c, PGconn *conn);
 extern int	pqGets(PQExpBuffer buf, PGconn *conn);