diff --git a/Makefile b/Makefile
index f0a571f3..43f816ff 100755
--- a/Makefile
+++ b/Makefile
@@ -28,7 +28,10 @@ REGRESS		:= plr
 EXTRA_CLEAN	:= doc/HTML.index
 
 ifdef USE_PGXS
-PGXS := $(shell pg_config --pgxs)
+ifndef PG_CONFIG
+PG_CONFIG := pg_config
+endif
+PGXS := $(shell $(PG_CONFIG) --pgxs)
 include $(PGXS)
 else
 subdir = contrib/plr
diff --git a/doc/pg_doc b/doc/pg_doc
index 23c595a4..24771652 100755
--- a/doc/pg_doc
+++ b/doc/pg_doc
@@ -1,5 +1,5 @@
 #!/bin/bash
 
 jade -c ${DOCBOOKSTYLE}/catalog -d ../../../doc/src/sgml/stylesheet.dsl -i output-html -t sgml $1
-
-
+openjade  -D . -c ${DOCBOOKSTYLE}/catalog -d ../../../doc/src/sgml/stylesheet.dsl -t tex -V tex-backend -i output-print -V texpdf-output -V '%paper-type%'=USletter -o plr-US.tex-pdf $1
+pdfjadetex plr-US.tex-pdf
\ No newline at end of file
diff --git a/pg_conversion.c b/pg_conversion.c
index 5eb59895..677fcec5 100755
--- a/pg_conversion.c
+++ b/pg_conversion.c
@@ -1188,20 +1188,30 @@ get_frame_tuplestore(SEXP rval,
 			if(isFactor(dfcol))
 			{
 				SEXP t;
-				for (t = ATTRIB(dfcol); t != R_NilValue; t = CDR(t))
+
+				/*
+				 * a factor is a special type of integer
+				 * but must check for NA value first
+				 */
+				if (INTEGER_ELT(dfcol, i) != NA_INTEGER)
 				{
-					if(TAG(t) == R_LevelsSymbol)
+					for (t = ATTRIB(dfcol); t != R_NilValue; t = CDR(t))
 					{
-						SEXP	obj;
-						int		idx = INTEGER(dfcol)[i] - 1;
+						if(TAG(t) == R_LevelsSymbol)
+						{
+							SEXP	obj;
+							int		idx = INTEGER(dfcol)[i] - 1;
 
-						PROTECT(obj = CAR(t));
-						values[j] = pstrdup(CHAR(STRING_ELT(obj, idx)));
-						UNPROTECT(1);
+							PROTECT(obj = CAR(t));
+							values[j] = pstrdup(CHAR(STRING_ELT(obj, idx)));
+							UNPROTECT(1);
 
-						break;
+							break;
+						}
 					}
 				}
+				else
+					values[j] = NULL;
 			}
 			else
 			{
diff --git a/plr.h b/plr.h
index 56e97eb3..68e9a732 100755
--- a/plr.h
+++ b/plr.h
@@ -58,13 +58,18 @@
 #endif
 #include "Rinternals.h"
 #include "Rdefines.h"
+#if (R_VERSION < 133120) /* R_VERSION >= 2.8.0 */
 #include "Rdevices.h"
+#endif
 
 /* starting in R-2.7.0 this defn was removed from Rdevices.h */
 #ifndef KillAllDevices
 #define KillAllDevices					Rf_KillAllDevices
 #endif
 
+/* for some reason this is not in any R header files, it is locally defined */
+#define INTEGER_ELT(x,__i__)    INTEGER(x)[__i__]
+
 /*
  * The R headers define various symbols that are also defined by the
  * Postgres headers, so undef them first to avoid conflicts.