diff --git a/jerry-core/ecma/base/ecma-helpers-value.c b/jerry-core/ecma/base/ecma-helpers-value.c
index cc79baa9c0..ac9e85574a 100644
--- a/jerry-core/ecma/base/ecma-helpers-value.c
+++ b/jerry-core/ecma/base/ecma-helpers-value.c
@@ -569,13 +569,21 @@ ecma_make_length_value (ecma_length_t number) /**< number to be encoded */
 ecma_value_t
 ecma_make_number_value (ecma_number_t ecma_number) /**< number to be encoded */
 {
-  ecma_integer_value_t integer_value = (ecma_integer_value_t) ecma_number;
-
-  if ((ecma_number_t) integer_value == ecma_number
-      && ((integer_value == 0) ? ecma_is_number_equal_to_positive_zero (ecma_number)
-                               : ECMA_IS_INTEGER_NUMBER (integer_value)))
+  /* The value can only be stored as a simple integer when it is inside the
+   * ecma_integer_value_t range; converting a double outside of it (e.g. 1e308,
+   * or a number literal coming from a snapshot) is undefined behaviour and traps
+   * under -fsanitize=undefined. */
+  if (ecma_number >= (ecma_number_t) ECMA_INTEGER_NUMBER_MIN
+      && ecma_number <= (ecma_number_t) ECMA_INTEGER_NUMBER_MAX)
   {
-    return ecma_make_integer_value (integer_value);
+    ecma_integer_value_t integer_value = (ecma_integer_value_t) ecma_number;
+
+    if ((ecma_number_t) integer_value == ecma_number
+        && ((integer_value == 0) ? ecma_is_number_equal_to_positive_zero (ecma_number)
+                                 : ECMA_IS_INTEGER_NUMBER (integer_value)))
+    {
+      return ecma_make_integer_value (integer_value);
+    }
   }
 
   return ecma_create_float_number (ecma_number);
@@ -1010,15 +1018,22 @@ ecma_update_float_number (ecma_value_t float_value, /**< original float value */
 {
   JERRY_ASSERT (ecma_is_value_float_number (float_value));
 
-  ecma_integer_value_t integer_number = (ecma_integer_value_t) new_number;
   ecma_number_t *number_p = (ecma_number_t *) ecma_get_pointer_from_ecma_value (float_value);
 
-  if ((ecma_number_t) integer_number == new_number
-      && ((integer_number == 0) ? ecma_is_number_equal_to_positive_zero (new_number)
-                                : ECMA_IS_INTEGER_NUMBER (integer_number)))
+  /* See the note in ecma_make_number_value: the cast is only defined when the
+   * double is inside the ecma_integer_value_t range. */
+  if (new_number >= (ecma_number_t) ECMA_INTEGER_NUMBER_MIN
+      && new_number <= (ecma_number_t) ECMA_INTEGER_NUMBER_MAX)
   {
-    ecma_dealloc_number (number_p);
-    return ecma_make_integer_value (integer_number);
+    ecma_integer_value_t integer_number = (ecma_integer_value_t) new_number;
+
+    if ((ecma_number_t) integer_number == new_number
+        && ((integer_number == 0) ? ecma_is_number_equal_to_positive_zero (new_number)
+                                  : ECMA_IS_INTEGER_NUMBER (integer_number)))
+    {
+      ecma_dealloc_number (number_p);
+      return ecma_make_integer_value (integer_number);
+    }
   }
 
   *number_p = new_number;
@@ -1062,19 +1077,25 @@ void
 ecma_value_assign_number (ecma_value_t *value_p, /**< [in, out] ecma value */
                           ecma_number_t ecma_number) /**< number to assign */
 {
-  ecma_integer_value_t integer_value = (ecma_integer_value_t) ecma_number;
-
-  if ((ecma_number_t) integer_value == ecma_number
-      && ((integer_value == 0) ? ecma_is_number_equal_to_positive_zero (ecma_number)
-                               : ECMA_IS_INTEGER_NUMBER (integer_value)))
+  /* See the note in ecma_make_number_value: the cast is only defined when the
+   * double is inside the ecma_integer_value_t range. */
+  if (ecma_number >= (ecma_number_t) ECMA_INTEGER_NUMBER_MIN
+      && ecma_number <= (ecma_number_t) ECMA_INTEGER_NUMBER_MAX)
   {
-    if (ecma_get_value_type_field (*value_p) != ECMA_TYPE_DIRECT
-        && ecma_get_value_type_field (*value_p) != ECMA_TYPE_OBJECT)
+    ecma_integer_value_t integer_value = (ecma_integer_value_t) ecma_number;
+
+    if ((ecma_number_t) integer_value == ecma_number
+        && ((integer_value == 0) ? ecma_is_number_equal_to_positive_zero (ecma_number)
+                                 : ECMA_IS_INTEGER_NUMBER (integer_value)))
     {
-      ecma_free_value (*value_p);
+      if (ecma_get_value_type_field (*value_p) != ECMA_TYPE_DIRECT
+          && ecma_get_value_type_field (*value_p) != ECMA_TYPE_OBJECT)
+      {
+        ecma_free_value (*value_p);
+      }
+      *value_p = ecma_make_integer_value (integer_value);
+      return;
     }
-    *value_p = ecma_make_integer_value (integer_value);
-    return;
   }
 
   ecma_value_assign_float_number (value_p, ecma_number);
diff --git a/tests/unit-core/test-api-value-type.c b/tests/unit-core/test-api-value-type.c
index 9890c1eada..37d5c2dee4 100644
--- a/tests/unit-core/test-api-value-type.c
+++ b/tests/unit-core/test-api-value-type.c
@@ -147,6 +147,27 @@ main (void)
     jerry_set_realm (old_realm);
   }
 
+  /* Numbers outside the ecma_integer_value_t range must round-trip as float
+   * values.  Converting them to an integer to test for a small integer used to
+   * be undefined behaviour and trapped under -fsanitize=undefined. */
+  {
+    static const double out_of_range_numbers[] = { 1e308, -1e308, 1.5e300, -1.5e10, 1e18 };
+    for (size_t i = 0; i < sizeof (out_of_range_numbers) / sizeof (double); i++)
+    {
+      jerry_value_t value = jerry_number (out_of_range_numbers[i]);
+      TEST_ASSERT (!jerry_value_is_exception (value));
+      TEST_ASSERT (jerry_value_is_number (value));
+      TEST_ASSERT (jerry_value_as_number (value) == out_of_range_numbers[i]);
+      jerry_value_free (value);
+    }
+
+    /* Values inside the range must keep behaving as small integers. */
+    jerry_value_t small = jerry_number (42.0);
+    TEST_ASSERT (jerry_value_is_number (small));
+    TEST_ASSERT (jerry_value_as_number (small) == 42.0);
+    jerry_value_free (small);
+  }
+
   jerry_cleanup ();
 
   return 0;