diff --git a/Changes b/Changes
index 2254dda..45ba7c8 100644
--- a/Changes
+++ b/Changes
@@ -1,5 +1,7 @@
 2021-09-17:
 -----------
+* Release labltk-8.06.11 for ocaml 4.13
+* Disable -warn-error for users, add all-devel target for developers
 * Add ommitted labels
 * Update ocamlbrowser for ocaml 4.13
 
diff --git a/INSTALL b/INSTALL
index 07a8c2a..6f68868 100644
--- a/INSTALL
+++ b/INSTALL
@@ -3,7 +3,7 @@
 
 PREREQUISITES
 
-* OCaml (>= 4.08) should be installed  (4.12 for ocamlbrowse)
+* OCaml (>= 4.08) should be installed  (4.13 for ocamlbrowser)
 
 * Tcl/Tk (>= 8.03) should be installed
 
diff --git a/Makefile b/Makefile
index 69b47e3..93df431 100644
--- a/Makefile
+++ b/Makefile
@@ -19,8 +19,11 @@
 SUBDIRS=compiler support lib jpf frx examples_labltk \
 	examples_camltk browser
 SUBDIRS_GENERATED=camltk labltk
+WARNERR=-warn-error A-3
 include config/Makefile
 
+all-devel:
+	$(MAKE) all opt WARNERR="$(WARNERR)"
 all: library
 	cd browser; $(MAKE)
 opt: libraryopt
diff --git a/support/Makefile.common b/support/Makefile.common
index d24d591..7aac0a2 100644
--- a/support/Makefile.common
+++ b/support/Makefile.common
@@ -22,10 +22,10 @@ include ../config/Makefile
 
 CAMLRUN=$(BINDIR)/ocamlrun
 CAMLC=$(BINDIR)/ocamlc$(OPT)
-CAMLOPT=$(BINDIR)/ocamlopt$(OPT)
+CAMLOPT=$(BINDIR)/ocamlopt$(OPT) $(WARNERR)
 CAMLCB=$(BINDIR)/ocamlc
 CAMLOPTB=$(BINDIR)/ocamlopt
-CAMLCOMP=$(CAMLC) -c -warn-error A-3
+CAMLCOMP=$(CAMLC) -c $(WARNERR)
 CAMLYACC=$(BINDIR)/ocamlyacc -v
 CAMLLEX=$(BINDIR)/ocamllex
 CAMLLIBR=$(CAMLC) -a