diff --git a/configure b/configure
index ec35de5ba65..3f91117f245 100755
--- a/configure
+++ b/configure
@@ -16853,6 +16853,39 @@ cat >>confdefs.h <<_ACEOF
 _ACEOF
 
 
+# The cast to long int works around a bug in the HP C Compiler
+# version HP92453-01 B.11.11.23709.GP, which incorrectly rejects
+# declarations like `int a3[[(sizeof (unsigned char)) >= 0]];'.
+# This bug is HP SR number 8606223364.
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking size of intmax_t" >&5
+$as_echo_n "checking size of intmax_t... " >&6; }
+if ${ac_cv_sizeof_intmax_t+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  if ac_fn_c_compute_int "$LINENO" "(long int) (sizeof (intmax_t))" "ac_cv_sizeof_intmax_t"        "$ac_includes_default"; then :
+
+else
+  if test "$ac_cv_type_intmax_t" = yes; then
+     { { $as_echo "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
+$as_echo "$as_me: error: in \`$ac_pwd':" >&2;}
+as_fn_error 77 "cannot compute sizeof (intmax_t)
+See \`config.log' for more details" "$LINENO" 5; }
+   else
+     ac_cv_sizeof_intmax_t=0
+   fi
+fi
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_sizeof_intmax_t" >&5
+$as_echo "$ac_cv_sizeof_intmax_t" >&6; }
+
+
+
+cat >>confdefs.h <<_ACEOF
+#define SIZEOF_INTMAX_T $ac_cv_sizeof_intmax_t
+_ACEOF
+
+
 
 # Determine memory alignment requirements for the basic C data types.
 
diff --git a/configure.ac b/configure.ac
index 7284f1ff622..8f390027403 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1983,6 +1983,7 @@ AC_CHECK_SIZEOF([void *])
 AC_CHECK_SIZEOF([size_t])
 AC_CHECK_SIZEOF([long])
 AC_CHECK_SIZEOF([long long])
+AC_CHECK_SIZEOF([intmax_t])
 
 # Determine memory alignment requirements for the basic C data types.
 
diff --git a/meson.build b/meson.build
index 622598546ae..718150e3ac0 100644
--- a/meson.build
+++ b/meson.build
@@ -1776,6 +1776,8 @@ cdata.set('SIZEOF_LONG', cc.sizeof('long', args: test_c_args))
 cdata.set('SIZEOF_LONG_LONG', cc.sizeof('long long', args: test_c_args))
 cdata.set('SIZEOF_VOID_P', cc.sizeof('void *', args: test_c_args))
 cdata.set('SIZEOF_SIZE_T', cc.sizeof('size_t', args: test_c_args))
+cdata.set('SIZEOF_INTMAX_T', cc.sizeof('intmax_t', args: test_c_args,
+                                       prefix: '#include <stdint.h>'))
 
 
 # Check if __int128 is a working 128 bit integer type, and if so
diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in
index b0b0cfdaf79..72434ce957e 100644
--- a/src/include/pg_config.h.in
+++ b/src/include/pg_config.h.in
@@ -645,6 +645,9 @@
    RELSEG_SIZE requires an initdb. */
 #undef RELSEG_SIZE
 
+/* The size of `intmax_t', as computed by sizeof. */
+#undef SIZEOF_INTMAX_T
+
 /* The size of `long', as computed by sizeof. */
 #undef SIZEOF_LONG
 
diff --git a/src/port/snprintf.c b/src/port/snprintf.c
index 6541182df6d..d914547fae2 100644
--- a/src/port/snprintf.c
+++ b/src/port/snprintf.c
@@ -563,6 +563,15 @@ nextch2:
 				else
 					longflag = 1;
 				goto nextch2;
+			case 'j':
+#if SIZEOF_INTMAX_T == SIZEOF_LONG
+				longflag = 1;
+#elif SIZEOF_INTMAX_T == SIZEOF_LONG_LONG
+				longlongflag = 1;
+#else
+#error "cannot find integer type of the same size as intmax_t"
+#endif
+				goto nextch2;
 			case 'z':
 #if SIZEOF_SIZE_T == SIZEOF_LONG
 				longflag = 1;
@@ -826,6 +835,15 @@ nextch1:
 				else
 					longflag = 1;
 				goto nextch1;
+			case 'j':
+#if SIZEOF_INTMAX_T == SIZEOF_LONG
+				longflag = 1;
+#elif SIZEOF_INTMAX_T == SIZEOF_LONG_LONG
+				longlongflag = 1;
+#else
+#error "cannot find integer type of the same size as intmax_t"
+#endif
+				goto nextch1;
 			case 'z':
 #if SIZEOF_SIZE_T == SIZEOF_LONG
 				longflag = 1;