diff --git a/src/backend/access/brin/brin_minmax_multi.c b/src/backend/access/brin/brin_minmax_multi.c
index 524c1846b8..a581659fe2 100644
--- a/src/backend/access/brin/brin_minmax_multi.c
+++ b/src/backend/access/brin/brin_minmax_multi.c
@@ -620,14 +620,18 @@ brin_range_serialize(Ranges *range)
 	 */
 	if (typlen == -1)			/* varlena */
 	{
-		for (int i = 0; i < nvalues; i++)
+		int			i;
+
+		for (i = 0; i < nvalues; i++)
 		{
 			len += VARSIZE_ANY(range->values[i]);
 		}
 	}
 	else if (typlen == -2)		/* cstring */
 	{
-		for (int i = 0; i < nvalues; i++)
+		int			i;
+
+		for (i = 0; i < nvalues; i++)
 		{
 			/* don't forget to include the null terminator ;-) */
 			len += strlen(DatumGetCString(range->values[i])) + 1;
diff --git a/src/backend/libpq/auth.c b/src/backend/libpq/auth.c
index f9d40fa1a0..1545ff9f16 100644
--- a/src/backend/libpq/auth.c
+++ b/src/backend/libpq/auth.c
@@ -1650,16 +1650,16 @@ interpret_ident_response(const char *ident_response,
 						return false;
 					else
 					{
-						int			j;	/* Index into *ident_user */
+						int			i;	/* Index into *ident_user */
 
 						cursor++;	/* Go over colon */
 						while (pg_isblank(*cursor))
 							cursor++;	/* skip blanks */
 						/* Rest of line is user name.  Copy it over. */
-						j = 0;
+						i = 0;
 						while (*cursor != '\r' && i < IDENT_USERNAME_MAX)
-							ident_user[j++] = *cursor++;
-						ident_user[j] = '\0';
+							ident_user[i++] = *cursor++;
+						ident_user[i] = '\0';
 						return true;
 					}
 				}
diff --git a/src/backend/statistics/mcv.c b/src/backend/statistics/mcv.c
index 91b9635dc0..6eeacb0d47 100644
--- a/src/backend/statistics/mcv.c
+++ b/src/backend/statistics/mcv.c
@@ -1861,6 +1861,7 @@ mcv_get_match_bitmap(PlannerInfo *root, List *clauses,
 		{
 			/* AND/OR clause, with all subclauses being compatible */
 
+			int			i;
 			BoolExpr   *bool_clause = ((BoolExpr *) clause);
 			List	   *bool_clauses = bool_clause->args;
 
@@ -1879,7 +1880,7 @@ mcv_get_match_bitmap(PlannerInfo *root, List *clauses,
 			 * current one. We need to consider if we're evaluating AND or OR
 			 * condition when merging the results.
 			 */
-			for (int i = 0; i < mcvlist->nitems; i++)
+			for (i = 0; i < mcvlist->nitems; i++)
 				matches[i] = RESULT_MERGE(matches[i], is_or, bool_matches[i]);
 
 			pfree(bool_matches);
@@ -1888,6 +1889,7 @@ mcv_get_match_bitmap(PlannerInfo *root, List *clauses,
 		{
 			/* NOT clause, with all subclauses compatible */
 
+			int			i;
 			BoolExpr   *not_clause = ((BoolExpr *) clause);
 			List	   *not_args = not_clause->args;
 
@@ -1906,7 +1908,7 @@ mcv_get_match_bitmap(PlannerInfo *root, List *clauses,
 			 * current one. We're handling a NOT clause, so invert the result
 			 * before merging it into the global bitmap.
 			 */
-			for (int i = 0; i < mcvlist->nitems; i++)
+			for (i = 0; i < mcvlist->nitems; i++)
 				matches[i] = RESULT_MERGE(matches[i], is_or, !not_matches[i]);
 
 			pfree(not_matches);
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index c0d09edf9d..ca4ad07004 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -11775,10 +11775,11 @@ dumpFunc(Archive *fout, const FuncInfo *finfo)
 	if (*protrftypes)
 	{
 		Oid		   *typeids = palloc(FUNC_MAX_ARGS * sizeof(Oid));
+		int			i;
 
 		appendPQExpBufferStr(q, " TRANSFORM ");
 		parseOidArray(protrftypes, typeids, FUNC_MAX_ARGS);
-		for (int i = 0; typeids[i]; i++)
+		for (i = 0; typeids[i]; i++)
 		{
 			if (i != 0)
 				appendPQExpBufferStr(q, ", ");
diff --git a/src/interfaces/ecpg/pgtypeslib/numeric.c b/src/interfaces/ecpg/pgtypeslib/numeric.c
index b666c90908..35e7b92da4 100644
--- a/src/interfaces/ecpg/pgtypeslib/numeric.c
+++ b/src/interfaces/ecpg/pgtypeslib/numeric.c
@@ -1180,6 +1180,7 @@ PGTYPESnumeric_div(numeric *var1, numeric *var2, numeric *result)
 		{
 			if (divisor[guess].buf == NULL)
 			{
+				int			i;
 				long		sum = 0;
 
 				memcpy(&divisor[guess], &divisor[1], sizeof(numeric));
@@ -1187,7 +1188,7 @@ PGTYPESnumeric_div(numeric *var1, numeric *var2, numeric *result)
 				if (divisor[guess].buf == NULL)
 					goto done;
 				divisor[guess].digits = divisor[guess].buf;
-				for (int i = divisor[1].ndigits - 1; i >= 0; i--)
+				for (i = divisor[1].ndigits - 1; i >= 0; i--)
 				{
 					sum += divisor[1].digits[i] * guess;
 					divisor[guess].digits[i] = sum % 10;