diff --git a/GNUmakefile b/GNUmakefile
index b4c20bf..33ccb7f 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -1,12 +1,33 @@
+# This is the Makefile for Linux, macOS, and other systems
+# using GNU Make. For BSD users, look at the Makefile instead.
+# -------------------------------------------------------------
+
+# These are used when building and signing a release.
+
 VERSION ?= 2022.1
 KEYPAIR ?= 2022-01
+
+# -------------------------------------------------------------
+
+# Installation targets
+
 PREFIX ?= /usr/local
 DATADIR ?= $(PREFIX)/share/RETRO12
 DOCSDIR ?= $(PREFIX)/share/doc/RETRO12
 EXAMPLESDIR ?= $(PREFIX)/share/examples/RETRO12
 MANDIR ?= $(PREFIX)/share/man/man1
+
+# -------------------------------------------------------------
+
+# Flags for adding in libraries we need to link to.
+
+# If not using floating point, you can remove the `-lm` from
+# LIBM.
+
 LIBM ?= -lm
 
+# You can comment out this if not enabling the FFI.
+
 LIBDL ?=
 UNAME_S := $(shell uname -s)
 ifeq ($(UNAME_S),Linux)
@@ -15,6 +36,17 @@ endif
 
 CFLAGS ?= -O2
 
+# -------------------------------------------------------------
+
+# The I/O devices can be enabled or disabled. Comment or
+# uncomment the corresponding ENABLED and DEVICES lines and
+# then run `make`. Of particular note here, sockets support
+# is disabled by default and you may wish to enable it.
+#
+# Don't uncomment the line with -DNEEDS_STRL. I use the BSD
+# strl* functions and provide a copy of them when needed. GNU
+# libc does not include these.
+
 ENABLED ?=
 ENABLED += -DENABLE_FLOATS
 ENABLED += -DENABLE_FILES
@@ -39,10 +71,12 @@ DEVICES += interface/clock.retro
 DEVICES += interface/scripting.retro
 # DEVICES += interface/sockets.retro
 DEVICES += interface/sources.retro
-# DEVICES += interface/multicore.retro
+DEVICES += interface/multicore.retro
 DEVICES += interface/deprecated.retro
 DEVICES += interface/unsigned.retro
 
+# -------------------------------------------------------------
+
 all: build
 
 help:
diff --git a/Makefile b/Makefile
index 566fa7c..90c4177 100644
--- a/Makefile
+++ b/Makefile
@@ -1,16 +1,39 @@
-# Linux / macOS users: This Makefile is mainly intended for BSD
-#                      systems. You probably want to look at or
-#                      edit the GNUmakefile.
+# This is the Makefile for BSD systems. If using GNU Make (e.g.
+# on Linux or macOS), look at the GNUmakefile instead.
 # -------------------------------------------------------------
+
+# These are used when building and signing a release.
+
 VERSION ?= 2022.1
 KEYPAIR ?= 2022-01
+
+# -------------------------------------------------------------
+
+# Installation targets
+
 PREFIX ?= /usr/local
 DATADIR ?= $(PREFIX)/share/RETRO12
 DOCSDIR ?= $(PREFIX)/share/doc/RETRO12
 EXAMPLESDIR ?= $(PREFIX)/share/examples/RETRO12
 MANDIR ?= $(PREFIX)/man/man1
-LIBM ?= -lm -g
+
+# -------------------------------------------------------------
+
+# Flags for adding in libraries we need to link to.
+
+# If not using floating point, you can remove the `-lm` from
+# LIBM.
+
+LIBM ?= -lm
 LIBDL ?=
+
+# -------------------------------------------------------------
+
+# The I/O devices can be enabled or disabled. Comment or
+# uncomment the corresponding ENABLED and DEVICES lines and
+# then run `make`. Of particular note here, sockets support
+# is disabled by default and you may wish to enable it.
+
 ENABLED ?=
 ENABLED += -DENABLE_FLOATS
 ENABLED += -DENABLE_FILES
@@ -37,6 +60,8 @@ DEVICES += interface/multicore.retro
 DEVICES += interface/unsigned.retro
 DEVICES += interface/deprecated.retro
 
+# -------------------------------------------------------------
+
 all: build
 
 help:
@@ -206,7 +231,6 @@ doc/Glossary-Names-and-Stack.txt: bin/retro sorted
 	./bin/retro tools/glossary.retro export concise-stack >doc/Glossary-Names-and-Stack.txt
 
 
-
 # other targets
 
 release: clean build glossary