diff --git a/doc/src/sgml/ref/pgbench.sgml b/doc/src/sgml/ref/pgbench.sgml
index 5ced63edbe..41de1e2364 100644
--- a/doc/src/sgml/ref/pgbench.sgml
+++ b/doc/src/sgml/ref/pgbench.sgml
@@ -899,7 +899,7 @@ pgbench <optional> <replaceable>options</replaceable> </optional> <replaceable>d
   <para>
    There is a simple variable-substitution facility for script files.
    Variable names must consist of letters (including non-Latin letters),
-   digits, and underscores.
+   digits, and underscores, with the first character not being a digit.
    Variables can be set by the command-line <option>-D</option> option,
    explained above, or by the meta commands explained below.
    In addition to any variables preset by <option>-D</option> command-line options,
diff --git a/src/bin/pgbench/pgbench.c b/src/bin/pgbench/pgbench.c
index bb3e6f794c..0a7a3b29a8 100644
--- a/src/bin/pgbench/pgbench.c
+++ b/src/bin/pgbench/pgbench.c
@@ -1322,6 +1322,7 @@ makeVariableValue(Variable *var)
  * "src/bin/pgbench/exprscan.l".  Also see parseVariable(), below.
  *
  * Note: this static function is copied from "src/bin/psql/variables.c"
+ * but changed to disallow variable names starting with a digit.
  */
 static bool
 valid_variable_name(const char *name)
@@ -1332,6 +1333,15 @@ valid_variable_name(const char *name)
 	if (*ptr == '\0')
 		return false;
 
+	/* must not start with [0-9] */
+	if (IS_HIGHBIT_SET(*ptr) ||
+		strchr("ABCDEFGHIJKLMNOPQRSTUVWXYZ" "abcdefghijklmnopqrstuvwxyz"
+			   "_", *ptr) != NULL)
+		ptr++;
+	else
+		return false;
+
+	/* remaining characters can include [0-9] */
 	while (*ptr)
 	{
 		if (IS_HIGHBIT_SET(*ptr) ||
@@ -1453,23 +1463,27 @@ putVariableInt(CState *st, const char *context, char *name, int64 value)
  *
  * "sql" points at a colon.  If what follows it looks like a valid
  * variable name, return a malloc'd string containing the variable name,
- * and set *eaten to the number of characters consumed.
+ * and set *eaten to the number of characters consumed (including the colon).
  * Otherwise, return NULL.
  */
 static char *
 parseVariable(const char *sql, int *eaten)
 {
-	int			i = 0;
+	int			i = 1;			/* starting at 1 skips the colon */
 	char	   *name;
 
-	do
-	{
+	/* keep this logic in sync with valid_variable_name() */
+	if (IS_HIGHBIT_SET(sql[i]) ||
+		strchr("ABCDEFGHIJKLMNOPQRSTUVWXYZ" "abcdefghijklmnopqrstuvwxyz"
+			   "_", sql[i]) != NULL)
+		i++;
+	else
+		return NULL;
+
+	while (IS_HIGHBIT_SET(sql[i]) ||
+		   strchr("ABCDEFGHIJKLMNOPQRSTUVWXYZ" "abcdefghijklmnopqrstuvwxyz"
+				  "_0123456789", sql[i]) != NULL)
 		i++;
-	} while (IS_HIGHBIT_SET(sql[i]) ||
-			 strchr("ABCDEFGHIJKLMNOPQRSTUVWXYZ" "abcdefghijklmnopqrstuvwxyz"
-					"_0123456789", sql[i]) != NULL);
-	if (i == 1)
-		return NULL;			/* no valid variable name chars */
 
 	name = pg_malloc(i);
 	memcpy(name, &sql[1], i - 1);