diff --git a/ext/gmp/gmp.c b/ext/gmp/gmp.c
index b5451b8035e37..e0b64e8dfed5c 100644
--- a/ext/gmp/gmp.c
+++ b/ext/gmp/gmp.c
@@ -372,6 +372,15 @@ static zend_result shift_operator_helper(gmp_binary_ui_op_t op, zval *return_val
 			goto typeof_op_failure;
 		}
 
+		if (shift > INT_MAX / 1000) {
+			zend_throw_error(
+				zend_ce_value_error, "%s must be less than %d",
+				opcode == ZEND_POW ? "Exponent" : "Shift",
+				(INT_MAX / 1000)
+			);
+			ZVAL_UNDEF(return_value);
+			return FAILURE;
+		}
 		INIT_GMP_RETVAL(gmpnum_result);
 		op(gmpnum_result, gmpnum_op, (gmp_ulong) shift);
 		return SUCCESS;
diff --git a/ext/gmp/tests/bug16502.phpt b/ext/gmp/tests/bug16502.phpt
new file mode 100644
index 0000000000000..965405cff5256
--- /dev/null
+++ b/ext/gmp/tests/bug16502.phpt
@@ -0,0 +1,17 @@
+--TEST--
+pow() with GMP exponent too large should throw ValueError
+--EXTENSIONS--
+gmp
+--FILE--
+<?php
+$a = gmp_init(10000000000);
+
+try {
+    pow($a, $a);
+    echo "NO_EXCEPTION\n";
+} catch (ValueError $e) {
+    echo $e->getMessage(), "\n";
+}
+?>
+--EXPECTREGEX--
+Exponent must be less than [0-9]+
\ No newline at end of file