diff --git a/ci/aarch64-windows-debug.ps1 b/ci/aarch64-windows-debug.ps1
index f357373bc2f29111a0fae695eae1abe4e25d3704..f1d48e39d48ab49530ef98d4e7e018463f33fb05 100644
--- a/ci/aarch64-windows-debug.ps1
+++ b/ci/aarch64-windows-debug.ps1
@@ -56,3 +56,18 @@ stage3-debug\bin\zig.exe build test docs `
   -Denable-symlinks-windows `
   --test-timeout 30m
 CheckLastExitCode
+
+Write-Output "Build and test stage4..."
+stage3-debug\bin\zig.exe build `
+  --prefix stage4-debug `
+  -Denable-llvm `
+  -Dno-lib `
+  -Doptimize=Debug `
+  -Dtarget="$TARGET" `
+  -Dcpu="$MCPU" `
+  -Duse-zig-libcxx `
+  -Dversion-string="$(stage3-debug\bin\zig.exe version)"
+CheckLastExitCode
+
+stage4-debug\bin\zig.exe test ..\test\behavior.zig
+CheckLastExitCode
diff --git a/ci/x86_64-windows-debug.ps1 b/ci/x86_64-windows-debug.ps1
index 162e901e791af0cf4feaf5b3a7600bdc57e858d5..451eb3d8299d2ab2584fe07807c7280b3673d6aa 100644
--- a/ci/x86_64-windows-debug.ps1
+++ b/ci/x86_64-windows-debug.ps1
@@ -57,6 +57,21 @@ stage3-debug\bin\zig.exe build test docs `
   --test-timeout 30m
 CheckLastExitCode
 
+Write-Output "Build and test stage4..."
+stage3-debug\bin\zig.exe build `
+  --prefix stage4-debug `
+  -Denable-llvm `
+  -Dno-lib `
+  -Doptimize=Debug `
+  -Dtarget="$TARGET" `
+  -Dcpu="$MCPU" `
+  -Duse-zig-libcxx `
+  -Dversion-string="$(stage3-debug\bin\zig.exe version)"
+CheckLastExitCode
+
+stage4-debug\bin\zig.exe test ..\test\behavior.zig
+CheckLastExitCode
+
 Write-Output "Build x86_64-windows-msvc behavior tests using the C backend..."
 stage3-debug\bin\zig.exe build-obj `
   -ofmt=c `