diff --git a/.github/workflows/build.yaml b/.github/workflows/build.yaml
index fea9c11..6dc32cc 100644
--- a/.github/workflows/build.yaml
+++ b/.github/workflows/build.yaml
@@ -84,10 +84,7 @@ jobs:
       env:
         BASH_COMPAT: 3.2
       run: |-
-        brew install make;
-        export PATH="/opt/homebrew/opt/make/libexec/gnubin:${PATH}";
-        make --version;
-        make --file=config/Makefile.base --trace test-self
+        make --file=config/Makefile.base test-self
 
   release:
     runs-on: ubuntu-latest
diff --git a/config/Makefile.base b/config/Makefile.base
index 26ec690..df820d5 100644
--- a/config/Makefile.base
+++ b/config/Makefile.base
@@ -2,10 +2,9 @@
 SHELL := /bin/bash
 
 # Setup variables for special purposes.
-NULL :=
 COMMA := ,
-SPACE := $(NULL) $(NULL)
-TAB := $(NULL)	$(NULL)
+SPACE := $() $()
+TAB := $()	$()
 define NEWLINE
 
 
@@ -46,7 +45,6 @@ endif
 
 # System depdendent helper functions.
 ifeq ("$(shell uname)","Linux")
-  MAKESHELL := PATH=$(PATH) /bin/bash
 else ifeq ($(shell uname),Darwin)
   path-setup = $(shell \
 	if [ "$(1)" == "opt" ]; then \
@@ -62,7 +60,8 @@ else ifeq ($(shell uname),Darwin)
   export PATH := $(call path-setup,opt,gsed,sed,$(PATH))
   export PATH := $(call path-setup,opt,make,make,$(PATH))
   # Ensure export of path to $(shell ...) in gmake 3.81.
-  MAKESHELL := PATH=$(PATH) /bin/bash
+  SHELL := PATH="$(PATH)" /bin/bash
+  .ONESHELL:
 else
   $(call cerror,unsupported operating system [$(shell uname --all)])
 endif