diff --git a/.github/workflows/build-on-pull-request.yml b/.github/workflows/build-on-pull-request.yml
index 41a3529b8..7f09ec6af 100644
--- a/.github/workflows/build-on-pull-request.yml
+++ b/.github/workflows/build-on-pull-request.yml
@@ -98,8 +98,6 @@ jobs:
       - name: Test that the targettest programs can be built.
         shell: bash
         run: |
-            make SYS=c64 -C targettest all
-            make SYS=c64 -C targettest clean
             make SYS=apple2 -C targettest
             make SYS=apple2 -C targettest clean
             make SYS=apple2enh -C targettest
@@ -108,58 +106,58 @@ jobs:
             make SYS=atari -C targettest clean
             make SYS=atarixl -C targettest
             make SYS=atarixl -C targettest clean
-            # make SYS=atari2600 -C targettest
-            # make SYS=atari2600 -C targettest clean
-            # make SYS=atari5200 -C targettest
-            # make SYS=atari5200 -C targettest clean
-            # make SYS=atmos -C targettest
-            # make SYS=atmos -C targettest clean
-            # make SYS=bbc -C targettest
-            # make SYS=bbc -C targettest clean
-            # make SYS=c128 -C targettest
-            # make SYS=c128 -C targettest clean
-            # make SYS=c16 -C targettest
-            # make SYS=c16 -C targettest clean
+            make SYS=atari2600 -C targettest
+            make SYS=atari2600 -C targettest clean
+            make SYS=atari5200 -C targettest
+            make SYS=atari5200 -C targettest clean
+            make SYS=atmos -C targettest
+            make SYS=atmos -C targettest clean
+            make SYS=bbc -C targettest
+            make SYS=bbc -C targettest clean
+            make SYS=c128 -C targettest
+            make SYS=c128 -C targettest clean
+            make SYS=c16 -C targettest
+            make SYS=c16 -C targettest clean
             make SYS=c64 -C targettest
             make SYS=c64 -C targettest clean
-            # make SYS=cbm510 -C targettest
-            # make SYS=cbm510 -C targettest clean
-            # make SYS=cbm610 -C targettest
-            # make SYS=cbm610 -C targettest clean
-            # make SYS=creativision -C targettest
-            # make SYS=creativision -C targettest clean
-            # make SYS=cx16 -C targettest
-            # make SYS=cx16 -C targettest clean
-            # make SYS=gamate -C targettest
-            # make SYS=gamate -C targettest clean
-            # make SYS=geos-apple -C targettest
-            # make SYS=geos-apple -C targettest clean
-            # make SYS=geos-cbm -C targettest
-            # make SYS=geos-cbm -C targettest clean
-            # make SYS=lunix -C targettest
-            # make SYS=lunix -C targettest clean
-            # make SYS=lynx -C targettest
-            # make SYS=lynx -C targettest clean
-            # make SYS=nes -C targettest
-            # make SYS=nes -C targettest clean
-            # make SYS=osic1p -C targettest
-            # make SYS=osic1p -C targettest clean
-            # make SYS=pce -C targettest
-            # make SYS=pce -C targettest clean
-            # make SYS=pet -C targettest
-            # make SYS=pet -C targettest clean
-            # make SYS=plus4 -C targettest
-            # make SYS=plus4 -C targettest clean
-            # make SYS=sim6502 -C targettest
-            # make SYS=sim6502 -C targettest clean
-            # make SYS=sim65c02 -C targettest
-            # make SYS=sim65c02 -C targettest clean
-            # make SYS=supervision -C targettest
-            # make SYS=supervision -C targettest clean
-            # make SYS=sym1 -C targettest
-            # make SYS=sym1 -C targettest clean
-            # make SYS=telestrat -C targettest
-            # make SYS=telestrat -C targettest clean
+            make SYS=cbm510 -C targettest
+            make SYS=cbm510 -C targettest clean
+            make SYS=cbm610 -C targettest
+            make SYS=cbm610 -C targettest clean
+            make SYS=creativision -C targettest
+            make SYS=creativision -C targettest clean
+            make SYS=cx16 -C targettest
+            make SYS=cx16 -C targettest clean
+            make SYS=gamate -C targettest
+            make SYS=gamate -C targettest clean
+            make SYS=geos-apple -C targettest
+            make SYS=geos-apple -C targettest clean
+            make SYS=geos-cbm -C targettest
+            make SYS=geos-cbm -C targettest clean
+            make SYS=lunix -C targettest
+            make SYS=lunix -C targettest clean
+            make SYS=lynx -C targettest
+            make SYS=lynx -C targettest clean
+            make SYS=nes -C targettest
+            make SYS=nes -C targettest clean
+            make SYS=osic1p -C targettest
+            make SYS=osic1p -C targettest clean
+            make SYS=pce -C targettest
+            make SYS=pce -C targettest clean
+            make SYS=pet -C targettest
+            make SYS=pet -C targettest clean
+            make SYS=plus4 -C targettest
+            make SYS=plus4 -C targettest clean
+            make SYS=sim6502 -C targettest
+            make SYS=sim6502 -C targettest clean
+            make SYS=sim65c02 -C targettest
+            make SYS=sim65c02 -C targettest clean
+            make SYS=supervision -C targettest
+            make SYS=supervision -C targettest clean
+            make SYS=sym1 -C targettest
+            make SYS=sym1 -C targettest clean
+            make SYS=telestrat -C targettest
+            make SYS=telestrat -C targettest clean
             make SYS=vic20 -C targettest
             make SYS=vic20 -C targettest clean
       - name: Build the document files.
@@ -189,8 +187,3 @@ jobs:
 
       - name: Build app (release)
         run: msbuild src\cc65.sln -t:rebuild -property:Configuration=Release
-
-# TODO: fix targettest Makefile for all currently commented out targets
-# TODO: build targettest cbm subdir for all cbm targets
-# TODO: build targettest atari subdir for all atari targets
-# TODO: build targettest apple2 subdir for all apple2 targets