diff --git a/com_redhat_kdump/gui/spokes/kdump.py b/com_redhat_kdump/gui/spokes/kdump.py
index f9de748..c313f43 100644
--- a/com_redhat_kdump/gui/spokes/kdump.py
+++ b/com_redhat_kdump/gui/spokes/kdump.py
@@ -144,7 +144,7 @@ def apply(self):
         if self._autoButton.get_active():
             self._proxy.ReservedMemory = "auto"
         else:
-            self._proxy.ReservedMemory = "%dM" % self._toBeReservedSpin.get_value_as_int()
+            self._proxy.ReservedMemory = "%d" % self._toBeReservedSpin.get_value_as_int()
         self._proxy.FadumpEnabled = self._fadumpButton.get_active()
 
         # This hub have been visited, use should now be aware of the crypted devices issue
diff --git a/com_redhat_kdump/service/kdump.py b/com_redhat_kdump/service/kdump.py
index 3f2a14c..db743f6 100755
--- a/com_redhat_kdump/service/kdump.py
+++ b/com_redhat_kdump/service/kdump.py
@@ -49,6 +49,7 @@ def __init__(self):
 
         self._reserved_memory = "auto"
         self.reserved_memory_changed = Signal()
+        self._lower, self._upper, self._step = getMemoryBounds()
 
     def publish(self):
         """Publish the DBus objects."""
@@ -85,6 +86,11 @@ def reserved_memory(self):
 
     @reserved_memory.setter
     def reserved_memory(self, value):
+        if value != "auto":
+            if int(value) > self._upper:
+                value = str(int(self._upper))
+            if int(value) < self._lower:
+                value = str(int(self._lower))
         self._reserved_memory = value
         self.reserved_memory_changed.emit()
         log.debug("Reserved memory is set to '%s'.", value)
diff --git a/test/unit_tests/test_interface.py b/test/unit_tests/test_interface.py
index dbac003..d765fc7 100644
--- a/test/unit_tests/test_interface.py
+++ b/test/unit_tests/test_interface.py
@@ -1,11 +1,22 @@
 from unittest.case import TestCase
+from unittest.mock import patch
 from unittest.mock import Mock
 
 from com_redhat_kdump import common
+from .mock import MockBuiltinRead
 from com_redhat_kdump.constants import KDUMP
 from com_redhat_kdump.service.kdump import KdumpService
 from com_redhat_kdump.service.kdump_interface import KdumpInterface
 
+SYS_CRASH_SIZE = '/sys/kernel/kexec_crash_size'
+PROC_MEMINFO = '/proc/meminfo'
+
+AARCH64_NFO_FIXTURE = {
+    SYS_CRASH_SIZE: "536870912",  # 512MB
+    PROC_MEMINFO:"""MemTotal:       2097152 kB
+"""  # 2GB - 512MB
+}
+
 
 class PropertiesChangedCallback(Mock):
 
@@ -48,7 +59,11 @@ def test_fadump_enabled(self):
         self._check_properties_changed("FadumpEnabled", True)
         self.assertEqual(self._interface.FadumpEnabled, True)
 
-    def test_reserved_memory(self):
+    @patch("builtins.open", MockBuiltinRead(AARCH64_NFO_FIXTURE))
+    @patch("blivet.arch.get_arch", return_value="aarch64")
+    def test_reserved_memory_aarch64(self):
+        self._service.__init__()
         self._interface.ReservedMemory = "256"
-        self._check_properties_changed("ReservedMemory", "256")
-        self.assertEqual(self._interface.ReservedMemory, "256")
+        self._check_properties_changed("ReservedMemory", "512")
+        self.assertEqual(self._interface.ReservedMemory, "512")
+
diff --git a/test/unit_tests/test_kickstart.py b/test/unit_tests/test_kickstart.py
index 746c242..38de810 100644
--- a/test/unit_tests/test_kickstart.py
+++ b/test/unit_tests/test_kickstart.py
@@ -1,8 +1,19 @@
 from textwrap import dedent
 from unittest.case import TestCase
+from unittest.mock import patch
 from com_redhat_kdump import common
+from .mock import MockBuiltinRead
 from com_redhat_kdump.service.kdump import KdumpService
 
+SYS_CRASH_SIZE = '/sys/kernel/kexec_crash_size'
+PROC_MEMINFO = '/proc/meminfo'
+
+X86_LOWER_INFO_FIXTURE = {
+    SYS_CRASH_SIZE: "167772160",  # 160MB
+    PROC_MEMINFO:"""MemTotal:        1048576 kB
+"""  # 1GB - 160MB
+}
+
 
 class KdumpKickstartTestCase(TestCase):
 
@@ -68,18 +79,21 @@ def test_ks_disable(self):
         %end
         """)
 
-    def test_ks_reserve_mb(self):
+    @patch("builtins.open", MockBuiltinRead(X86_LOWER_INFO_FIXTURE))
+    @patch("blivet.arch.get_arch", return_value="x86_64")
+    def test_ks_reserve_mb_x86_with_up(self, _mock_read):
+        self._service.__init__()
         self._check_ks_input("""
-        %addon com_redhat_kdump --enable --reserve-mb=256
+        %addon com_redhat_kdump --enable --reserve-mb=600
         %end
         """)
 
         self.assertEqual(self._service.kdump_enabled, True)
         self.assertEqual(self._service.fadump_enabled, False)
-        self.assertEqual(self._service.reserved_memory, "256")
+        self.assertEqual(self._service.reserved_memory, "512") # upper = 1024M - 512M
 
         self._check_ks_output("""
-        %addon com_redhat_kdump --enable --reserve-mb='256'
+        %addon com_redhat_kdump --enable --reserve-mb='512'
 
         %end
         """)