diff --git a/hooks/ceph_hooks.py b/hooks/ceph_hooks.py
index 474389a2..f7c4bef1 100755
--- a/hooks/ceph_hooks.py
+++ b/hooks/ceph_hooks.py
@@ -386,6 +386,17 @@ def warn_if_memory_outside_bounds(value):
             "This is not recommended.", level=WARNING)
 
 
+def is_tune_osd_memory_target_valid() -> bool:
+    """
+    Check if the tune-osd-memory-target value is valid
+
+    :returns: True if valid, else False
+    :rtype: bool
+    """
+    value = config('tune-osd-memory-target')
+    return not value or bool(re.match(r"\d+(?:GB|%)$", value))
+
+
 def get_osd_memory_target():
     """
     Processes the config value of tune-osd-memory-target.
@@ -868,6 +879,11 @@ VERSION_PACKAGE = 'ceph-common'
 
 def assess_status():
     """Assess status of current unit"""
+
+    if not is_tune_osd_memory_target_valid():
+        status_set('blocked', 'tune-osd-memory-target config value is invalid')
+        return
+
     # check to see if the unit is paused.
     application_version_set(get_upstream_version(VERSION_PACKAGE))
     if is_unit_upgrading_set():
diff --git a/unit_tests/test_ceph_hooks.py b/unit_tests/test_ceph_hooks.py
index 2bfa2d3c..a127c601 100644
--- a/unit_tests/test_ceph_hooks.py
+++ b/unit_tests/test_ceph_hooks.py
@@ -737,6 +737,37 @@ class CephHooksTestCase(unittest.TestCase):
             level=ceph_hooks.WARNING
         )
 
+    @patch.object(ceph_hooks, "config")
+    def test_is_tune_osd_memory_target_valid(self, mock_config):
+        def tune(value):
+            return lambda k: (
+                value if k == "tune-osd-memory-target" else KeyError
+            )
+
+        # value, is_valid
+        scenarios = [
+            ("", True),
+            ("5GB", True),
+            ("020GB", True),
+            ("34GB", True),
+            ("5%", True),
+            ("05%", True),
+            ("50%", True),
+            ("test", False),
+            ("   ", False),
+            ("5", False),
+            ("GB", False),
+            ("%", False),
+            ("test5GB", False),
+            ("50%%", False),
+        ]
+        for value, expected_valid in scenarios:
+            mock_config.side_effect = tune(value)
+            self.assertEqual(
+                ceph_hooks.is_tune_osd_memory_target_valid(),
+                expected_valid
+            )
+
     @patch.object(ceph_hooks, "config")
     @patch.object(ceph_hooks, "get_total_ram")
     @patch.object(ceph_hooks, "kv")