diff --git a/mysql-test/r/insert.result b/mysql-test/r/insert.result
index 8dbba4d454a..a884b51eada 100644
--- a/mysql-test/r/insert.result
+++ b/mysql-test/r/insert.result
@@ -499,4 +499,18 @@ i
 2
 2
 DROP TABLE t1, t2;
+CREATE TABLE t1 (c1 INT NOT NULL);
+INSERT INTO t1 VALUES(4188.32999999999992724042385816574096679687500),
+('4188.32999999999992724042385816574096679687500'), (4188);
+SELECT * FROM t1;
+c1
+4188
+4188
+4188
+CREATE TABLE t2 (c1 BIGINT);
+INSERT INTO t2 VALUES('15449237462.0000000000');
+SELECT * FROM t2;
+c1
+15449237462
+DROP TABLE t1, t2;
 End of 5.0 tests.
diff --git a/mysql-test/t/insert.test b/mysql-test/t/insert.test
index 3d32da9c3b7..59da875bb24 100644
--- a/mysql-test/t/insert.test
+++ b/mysql-test/t/insert.test
@@ -387,5 +387,20 @@ SELECT * FROM t2;
 
 DROP TABLE t1, t2;
 
+#
+# Bug #30453: String not cast to int correctly
+#
+
+CREATE TABLE t1 (c1 INT NOT NULL);
+INSERT INTO t1 VALUES(4188.32999999999992724042385816574096679687500),
+('4188.32999999999992724042385816574096679687500'), (4188);
+SELECT * FROM t1;
+
+CREATE TABLE t2 (c1 BIGINT);
+INSERT INTO t2 VALUES('15449237462.0000000000');
+SELECT * FROM t2;
+
+DROP TABLE t1, t2;
+
 --echo End of 5.0 tests.
 
diff --git a/strings/ctype-simple.c b/strings/ctype-simple.c
index 6b71f29f0d2..b5e5e2184ba 100644
--- a/strings/ctype-simple.c
+++ b/strings/ctype-simple.c
@@ -1561,14 +1561,18 @@ my_strntoull10rnd_8bit(CHARSET_INFO *cs __attribute__((unused)),
       }
       else
         addon= (*str >= '5');
-      for ( ; str < end && (ch= (uchar) (*str - '0')) < 10; str++)
+      if (!dot)
       {
-        if (!dot)
-          shift++;
+        for ( ; str < end && (ch= (uchar) (*str - '0')) < 10; shift++, str++);
+        if (str < end && *str == '.')
+        {
+          str++;
+          for ( ; str < end && (ch= (uchar) (*str - '0')) < 10; str++);
+        }
       }
-      if (str < end && *str == '.' && !dot)
+      else
       {
-        str++;
+        shift= dot - str;
         for ( ; str < end && (ch= (uchar) (*str - '0')) < 10; str++);
       }
       goto exp;