diff --git a/NEWS.md b/NEWS.md
index 7d2bc58b..3fe55f6b 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,3 +1,8 @@
+# mlr3misc 0.12.0-9000
+
+* fix: Fixed an important bug that caused serialized objects to be overly large
+when installing mlr3 with `--with-keep.source` (#88)
+
 # mlr3misc 0.12.0
 
 * Added new encapsulation mode `"try"`.
diff --git a/R/leanify.R b/R/leanify.R
index ea8b217a..9cd6bcf4 100644
--- a/R/leanify.R
+++ b/R/leanify.R
@@ -43,6 +43,10 @@ leanificate_method = function(cls, fname, env = cls$parent_env) {
   environment(replacingfn) = environment(fn)
 
   function_kind = switch(function_kind_container, public_methods = "public", private_methods = "private", active = "active")
+  # We remove the srcref (which exists when installing with option --with-keep.source) because:
+  # (1) incorrect rendering of leanified functions
+  # (2) use up memory unnecessarily
+  origattributes$srcref = NULL
   attributes(replacingfn) = origattributes
   cls$set(function_kind, fname, replacingfn, overwrite = TRUE)
 }