diff --git a/rust/rhg/src/main.rs b/rust/rhg/src/main.rs
--- a/rust/rhg/src/main.rs
+++ b/rust/rhg/src/main.rs
@@ -687,13 +687,18 @@ fn check_extensions(config: &Config) -> 
     }
 
     let enabled: HashSet<&[u8]> = config
-        .get_section_keys(b"extensions")
-        .into_iter()
-        .map(|extension| {
+        .iter_section(b"extensions")
+        .filter_map(|(extension, value)| {
+            if value == b"!" {
+                // Filter out disabled extensions
+                return None;
+            }
             // Ignore extension suboptions. Only `required` exists for now.
             // `rhg` either supports an extension or doesn't, so it doesn't
             // make sense to consider the loading of an extension.
-            extension.split_2(b':').unwrap_or((extension, b"")).0
+            let actual_extension =
+                extension.split_2(b':').unwrap_or((extension, b"")).0;
+            Some(actual_extension)
         })
         .collect();
 
diff --git a/tests/test-log.t b/tests/test-log.t
--- a/tests/test-log.t
+++ b/tests/test-log.t
@@ -2157,6 +2157,8 @@ test -u/-k for problematic encoding
   ... '''.encode('utf-8')) and None
   $ sh < setup.sh
 
+#if no-rhg
+
 test in problematic encoding
   >>> with open('test.sh', 'wb') as f:
   ...     f.write(u'''
@@ -2179,6 +2181,8 @@ test in problematic encoding
   3
   1
 
+#endif
+
   $ cd ..
 
 test hg log on non-existent files and on directories