diff --git a/.github/workflows/test-devel.yml b/.github/workflows/test-devel.yml
index 47e23d8..7173c8c 100644
--- a/.github/workflows/test-devel.yml
+++ b/.github/workflows/test-devel.yml
@@ -149,9 +149,13 @@ jobs:
     - name: Build InspIRCd
       run: |
         cd $GITHUB_WORKSPACE/inspircd/
-        patch src/inspircd.cpp < $GITHUB_WORKSPACE/patches/inspircd_mainloop.patch
+
+        # Insp3 <= 3.16.0 and Insp4 <= 4.0.0a21 don't support -DINSPIRCD_UNLIMITED_MAINLOOP
+        patch src/inspircd.cpp < $GITHUB_WORKSPACE/patches/inspircd_mainloop.patch || true
+
         ./configure --prefix=$HOME/.local/inspircd --development
-        make -j 4
+
+        CXXFLAGS=-DINSPIRCD_UNLIMITED_MAINLOOP make -j 4
         make install
     - name: Make artefact tarball
       run: cd ~; tar -czf artefacts-inspircd.tar.gz .local/ go/
diff --git a/.github/workflows/test-devel_release.yml b/.github/workflows/test-devel_release.yml
index 2bdd1b5..2188cfd 100644
--- a/.github/workflows/test-devel_release.yml
+++ b/.github/workflows/test-devel_release.yml
@@ -61,9 +61,13 @@ jobs:
     - name: Build InspIRCd
       run: |
         cd $GITHUB_WORKSPACE/inspircd/
-        patch src/inspircd.cpp < $GITHUB_WORKSPACE/patches/inspircd_mainloop.patch
+
+        # Insp3 <= 3.16.0 and Insp4 <= 4.0.0a21 don't support -DINSPIRCD_UNLIMITED_MAINLOOP
+        patch src/inspircd.cpp < $GITHUB_WORKSPACE/patches/inspircd_mainloop.patch || true
+
         ./configure --prefix=$HOME/.local/inspircd --development
-        make -j 4
+
+        CXXFLAGS=-DINSPIRCD_UNLIMITED_MAINLOOP make -j 4
         make install
     - name: Make artefact tarball
       run: cd ~; tar -czf artefacts-inspircd.tar.gz .local/ go/
diff --git a/.github/workflows/test-stable.yml b/.github/workflows/test-stable.yml
index 3c6d556..c3863ac 100644
--- a/.github/workflows/test-stable.yml
+++ b/.github/workflows/test-stable.yml
@@ -189,9 +189,13 @@ jobs:
     - name: Build InspIRCd
       run: |
         cd $GITHUB_WORKSPACE/inspircd/
-        patch src/inspircd.cpp < $GITHUB_WORKSPACE/patches/inspircd_mainloop.patch
+
+        # Insp3 <= 3.16.0 and Insp4 <= 4.0.0a21 don't support -DINSPIRCD_UNLIMITED_MAINLOOP
+        patch src/inspircd.cpp < $GITHUB_WORKSPACE/patches/inspircd_mainloop.patch || true
+
         ./configure --prefix=$HOME/.local/inspircd --development
-        make -j 4
+
+        CXXFLAGS=-DINSPIRCD_UNLIMITED_MAINLOOP make -j 4
         make install
     - name: Make artefact tarball
       run: cd ~; tar -czf artefacts-inspircd.tar.gz .local/ go/
diff --git a/README.md b/README.md
index 605c553..e0f278a 100644
--- a/README.md
+++ b/README.md
@@ -110,8 +110,11 @@ cd /tmp/
 git clone https://github.com/inspircd/inspircd.git
 cd inspircd
 
-# optional, makes tests run considerably faster
+# Optional, makes tests run considerably faster. Pick one depending on the InspIRCd version:
+# on Insp3 <= 3.16.0 and Insp4 <= 4.0.0a21:
 patch src/inspircd.cpp < ~/irctest/patches/inspircd_mainloop.patch
+# on Insp3 >= 3.17.0 and Insp4 >= 4.0.0a22:
+export CXXFLAGS=-DINSPIRCD_UNLIMITED_MAINLOOP
 
 ./configure --prefix=$HOME/.local/ --development
 make -j 4
diff --git a/workflows.yml b/workflows.yml
index ee2b358..65e27e2 100644
--- a/workflows.yml
+++ b/workflows.yml
@@ -153,9 +153,13 @@ software:
         separate_build_job: true
         build_script: &inspircd_build_script |
             cd $GITHUB_WORKSPACE/inspircd/
-            patch src/inspircd.cpp < $GITHUB_WORKSPACE/patches/inspircd_mainloop.patch
+
+            # Insp3 <= 3.16.0 and Insp4 <= 4.0.0a21 don't support -DINSPIRCD_UNLIMITED_MAINLOOP
+            patch src/inspircd.cpp < $GITHUB_WORKSPACE/patches/inspircd_mainloop.patch || true
+
             ./configure --prefix=$HOME/.local/inspircd --development
-            make -j 4
+
+            CXXFLAGS=-DINSPIRCD_UNLIMITED_MAINLOOP make -j 4
             make install
     irc2:
         name: irc2