diff --git a/mysql-test/suite/rpl/r/mdev_38454.result b/mysql-test/suite/rpl/r/mdev_38454.result
new file mode 100644
index 0000000000000..fc848e381f037
--- /dev/null
+++ b/mysql-test/suite/rpl/r/mdev_38454.result
@@ -0,0 +1,13 @@
+# Testing master_connect_retry with + sign (expected to work)
+CHANGE MASTER TO master_connect_retry=+60;
+# Success
+# Testing master_connect_retry without + sign (expected to work)
+CHANGE MASTER TO master_connect_retry=60;
+# Success
+# Testing master_heartbeat_period with + sign (should work)
+CHANGE MASTER TO master_heartbeat_period=+60;
+# Testing both without + sign (should work)
+CHANGE MASTER TO master_connect_retry=60;
+CHANGE MASTER TO master_heartbeat_period=60;
+# Success
+RESET SLAVE ALL;
diff --git a/mysql-test/suite/rpl/t/mdev_38454.test b/mysql-test/suite/rpl/t/mdev_38454.test
new file mode 100644
index 0000000000000..8e1ce1b2dddd6
--- /dev/null
+++ b/mysql-test/suite/rpl/t/mdev_38454.test
@@ -0,0 +1,37 @@
+#
+# MDEV-38454: CHANGE MASTER TO master_heartbeat_period does not accept numbers with `+` sign
+#
+# Simple test to demonstrate the parser inconsistency has been fixed
+#
+
+#
+# Test master_connect_retry with explicit + sign (should work)
+#
+--echo # Testing master_connect_retry with + sign (expected to work)
+CHANGE MASTER TO master_connect_retry=+60;
+--echo # Success
+
+#
+# Test master_connect_retry without explicit + sign (should work)
+#
+--echo # Testing master_connect_retry without + sign (expected to work)
+CHANGE MASTER TO master_connect_retry=60;
+--echo # Success
+
+#
+# Test master_heartbeat_period with explicit + sign (should work after fix)
+#
+--echo # Testing master_heartbeat_period with + sign (should work)
+CHANGE MASTER TO master_heartbeat_period=+60;
+
+#
+# Test without + sign (should work for both)
+#
+--echo # Testing both without + sign (should work)
+CHANGE MASTER TO master_connect_retry=60;
+CHANGE MASTER TO master_heartbeat_period=60;
+--echo # Success
+
+
+# Reset
+RESET SLAVE ALL;
diff --git a/sql/sql_yacc.yy b/sql/sql_yacc.yy
index 2789c11b7c5c7..aae4a8a1d60fb 100644
--- a/sql/sql_yacc.yy
+++ b/sql/sql_yacc.yy
@@ -2384,9 +2384,9 @@ master_def:
             Lex->mi.ssl_crlpath= $3.str;
           }
 
-        | MASTER_HEARTBEAT_PERIOD_SYM '=' NUM_literal
+        | MASTER_HEARTBEAT_PERIOD_SYM '=' opt_plus NUM_literal
           {
-            Lex->mi.heartbeat_period= (float) $3->val_real();
+            Lex->mi.heartbeat_period= (float) $4->val_real();
             if (unlikely(Lex->mi.heartbeat_period >
                          SLAVE_MAX_HEARTBEAT_PERIOD) ||
                 unlikely(Lex->mi.heartbeat_period < 0.0))