diff --git a/src/bin/pgbench/pgbench.c b/src/bin/pgbench/pgbench.c
index f1d98be2d2..822461dce6 100644
--- a/src/bin/pgbench/pgbench.c
+++ b/src/bin/pgbench/pgbench.c
@@ -2861,7 +2861,18 @@ evaluateSleep(CState *st, int argc, char **argv, int *usecs)
 			pg_log_error("%s: undefined variable \"%s\"", argv[0], argv[1] + 1);
 			return false;
 		}
+
+		for (int i = 0; i < strlen(var); i++)
+		{
+			if(!isdigit(var[i]))
+			{
+				pg_log_error("\\sleep command argument must be an integer (not \"%s\")", var);
+				return false;
+			}
+		}
+
 		usec = atoi(var);
+
 	}
 	else
 		usec = atoi(argv[1]);
@@ -4648,7 +4659,7 @@ process_backslash_command(PsqlScanState sstate, const char *source)
 		 * will be parsed with atoi, which ignores trailing non-digit
 		 * characters.
 		 */
-		if (my_command->argc == 2 && my_command->argv[1][0] != ':')
+		if (my_command->argv[1][0] != ':')
 		{
 			char	   *c = my_command->argv[1];
 
@@ -4656,9 +4667,19 @@ process_backslash_command(PsqlScanState sstate, const char *source)
 				c++;
 			if (*c)
 			{
-				my_command->argv[2] = c;
-				offsets[2] = offsets[1] + (c - my_command->argv[1]);
-				my_command->argc = 3;
+				/* Raise an error if argv[1] does not start with a number */
+				if (my_command->argc == 2 && my_command->argv[1] != c)
+				{
+					my_command->argv[2] = c;
+					offsets[2] = offsets[1] + (c - my_command->argv[1]);
+					my_command->argc = 3;
+				}
+				else
+				{
+					syntax_error(source, lineno, my_command->first_line, my_command->argv[0],
+							 "\\sleep command argument must be an integer",
+							 my_command->argv[1], offsets[1] - start_offset);
+				}
 			}
 		}