diff --git a/src/interfaces/ecpg/include/pgtypes_date.h b/src/interfaces/ecpg/include/pgtypes_date.h
index 7ab8046b7b..b8990bb072 100644
--- a/src/interfaces/ecpg/include/pgtypes_date.h
+++ b/src/interfaces/ecpg/include/pgtypes_date.h
@@ -21,8 +21,8 @@ extern void PGTYPESdate_julmdy(date, int *);
 extern void PGTYPESdate_mdyjul(int *, date *);
 extern int	PGTYPESdate_dayofweek(date);
 extern void PGTYPESdate_today(date *);
-extern int	PGTYPESdate_defmt_asc(date *, char *, char *);
-extern int	PGTYPESdate_fmt_asc(date, char *, char *);
+extern int	PGTYPESdate_defmt_asc(date *, const char *, char *);
+extern int	PGTYPESdate_fmt_asc(date, const char *, char *);
 
 #ifdef __cplusplus
 }
diff --git a/src/interfaces/ecpg/include/pgtypes_timestamp.h b/src/interfaces/ecpg/include/pgtypes_timestamp.h
index 07e95294b3..537585ce21 100644
--- a/src/interfaces/ecpg/include/pgtypes_timestamp.h
+++ b/src/interfaces/ecpg/include/pgtypes_timestamp.h
@@ -22,9 +22,9 @@ extern		"C"
 extern timestamp PGTYPEStimestamp_from_asc(char *, char **);
 extern char *PGTYPEStimestamp_to_asc(timestamp);
 extern int	PGTYPEStimestamp_sub(timestamp *, timestamp *, interval *);
-extern int	PGTYPEStimestamp_fmt_asc(timestamp *, char *, int, char *);
+extern int	PGTYPEStimestamp_fmt_asc(timestamp *, char *, int, const char *);
 extern void PGTYPEStimestamp_current(timestamp *);
-extern int	PGTYPEStimestamp_defmt_asc(char *, char *, timestamp *);
+extern int	PGTYPEStimestamp_defmt_asc(char *, const char *, timestamp *);
 extern int	PGTYPEStimestamp_add_interval(timestamp * tin, interval * span, timestamp * tout);
 extern int	PGTYPEStimestamp_sub_interval(timestamp * tin, interval * span, timestamp * tout);
 
diff --git a/src/interfaces/ecpg/pgtypeslib/common.c b/src/interfaces/ecpg/pgtypeslib/common.c
index d800321a9d..9084fd06b4 100644
--- a/src/interfaces/ecpg/pgtypeslib/common.c
+++ b/src/interfaces/ecpg/pgtypeslib/common.c
@@ -16,7 +16,7 @@ pgtypes_alloc(long size)
 }
 
 char *
-pgtypes_strdup(char *str)
+pgtypes_strdup(const char *str)
 {
 	char	   *new = (char *) strdup(str);
 
diff --git a/src/interfaces/ecpg/pgtypeslib/datetime.c b/src/interfaces/ecpg/pgtypeslib/datetime.c
index 41377a6861..823626fcf5 100644
--- a/src/interfaces/ecpg/pgtypeslib/datetime.c
+++ b/src/interfaces/ecpg/pgtypeslib/datetime.c
@@ -173,7 +173,7 @@ PGTYPESdate_today(date * d)
 #define PGTYPES_FMTDATE_YEAR_DIGITS_LONG	6
 
 int
-PGTYPESdate_fmt_asc(date dDate, char *fmtstring, char *outbuf)
+PGTYPESdate_fmt_asc(date dDate, const char *fmtstring, char *outbuf)
 {
 	static struct
 	{
@@ -335,7 +335,7 @@ PGTYPESdate_fmt_asc(date dDate, char *fmtstring, char *outbuf)
 
 #define PGTYPES_DATE_MONTH_MAXLENGTH		20	/* probably even less  :-) */
 int
-PGTYPESdate_defmt_asc(date * d, char *fmt, char *str)
+PGTYPESdate_defmt_asc(date * d, const char *fmt, char *str)
 {
 	/*
 	 * token[2] = { 4,6 } means that token 2 starts at position 4 and ends at
diff --git a/src/interfaces/ecpg/pgtypeslib/extern.h b/src/interfaces/ecpg/pgtypeslib/extern.h
index c7c64b1578..88b2fb0775 100644
--- a/src/interfaces/ecpg/pgtypeslib/extern.h
+++ b/src/interfaces/ecpg/pgtypeslib/extern.h
@@ -37,7 +37,7 @@ union un_fmt_comb
 int			pgtypes_fmt_replace(union un_fmt_comb, int, char **, int *);
 
 char	   *pgtypes_alloc(long);
-char	   *pgtypes_strdup(char *);
+char	   *pgtypes_strdup(const char *);
 
 #ifndef bool
 #define bool char
diff --git a/src/interfaces/ecpg/pgtypeslib/timestamp.c b/src/interfaces/ecpg/pgtypeslib/timestamp.c
index 8d787bbbe6..dc5ff72b60 100644
--- a/src/interfaces/ecpg/pgtypeslib/timestamp.c
+++ b/src/interfaces/ecpg/pgtypeslib/timestamp.c
@@ -18,7 +18,7 @@
 #include "pgtypes_date.h"
 
 
-int PGTYPEStimestamp_defmt_scan(char **, char *, timestamp *, int *, int *, int *,
+int PGTYPEStimestamp_defmt_scan(char **, const char *, timestamp *, int *, int *, int *,
 							int *, int *, int *, int *);
 
 #ifdef HAVE_INT64_TIMESTAMP
@@ -384,12 +384,12 @@ PGTYPEStimestamp_current(timestamp * ts)
 
 static int
 dttofmtasc_replace(timestamp * ts, date dDate, int dow, struct tm * tm,
-				   char *output, int *pstr_len, char *fmtstr)
+				   char *output, int *pstr_len, const char *fmtstr)
 {
 	union un_fmt_comb replace_val;
 	int			replace_type;
 	int			i;
-	char	   *p = fmtstr;
+	const char *p = fmtstr;
 	char	   *q = output;
 
 	while (*p)
@@ -866,7 +866,7 @@ dttofmtasc_replace(timestamp * ts, date dDate, int dow, struct tm * tm,
 
 
 int
-PGTYPEStimestamp_fmt_asc(timestamp * ts, char *output, int str_len, char *fmtstr)
+PGTYPEStimestamp_fmt_asc(timestamp * ts, char *output, int str_len, const char *fmtstr)
 {
 	struct tm	tm;
 	fsec_t		fsec;
@@ -894,7 +894,7 @@ PGTYPEStimestamp_sub(timestamp * ts1, timestamp * ts2, interval * iv)
 }
 
 int
-PGTYPEStimestamp_defmt_asc(char *str, char *fmt, timestamp * d)
+PGTYPEStimestamp_defmt_asc(char *str, const char *fmt, timestamp * d)
 {
 	int			year,
 				month,