diff --git a/ci/aarch64-linux-debug.sh b/ci/aarch64-linux-debug.sh
index 94f40c557b9035b054f45be4f1be441180339a08..90ed8bbc35577aa16bad496b8eb475125dc8d85c 100644
--- a/ci/aarch64-linux-debug.sh
+++ b/ci/aarch64-linux-debug.sh
@@ -60,6 +60,7 @@ stage3-debug/bin/zig build -Dtarget=arm-linux-musleabihf
 # TODO: add -fqemu back to this line
 
 stage3-debug/bin/zig build test docs \
+  -j1 \
   -fwasmtime \
   -Dstatic-llvm \
   -Dtarget=native-native-musl \
diff --git a/ci/aarch64-linux-release.sh b/ci/aarch64-linux-release.sh
index 65d6063f250e1178255f450af36a9ec53503fd4b..e99e3e1c0864fed768e36f9adaf3e9f880237334 100644
--- a/ci/aarch64-linux-release.sh
+++ b/ci/aarch64-linux-release.sh
@@ -60,6 +60,7 @@ stage3-release/bin/zig build -Dtarget=arm-linux-musleabihf
 # TODO: add -fqemu back to this line
 
 stage3-release/bin/zig build test docs \
+  -j1 \
   -fwasmtime \
   -Dstatic-llvm \
   -Dtarget=native-native-musl \
diff --git a/ci/aarch64-macos.sh b/ci/aarch64-macos.sh
index b4533e149f2758faa53b94042e05d15362c6ee1f..634a60b6007eddee01a7a061c7330683dcccc3d1 100755
--- a/ci/aarch64-macos.sh
+++ b/ci/aarch64-macos.sh
@@ -44,6 +44,7 @@ PATH="$HOME/local/bin:$PATH" cmake .. \
 $HOME/local/bin/ninja install
 
 stage3-release/bin/zig build test docs \
+  -j1 \
   --zig-lib-dir "$(pwd)/../lib" \
   -Denable-macos-sdk \
   -Dstatic-llvm \
diff --git a/ci/x86_64-linux-debug.sh b/ci/x86_64-linux-debug.sh
index 7f2382f04a6961893cb50efe4a636287a5a6685e..1267a2d753cec146a0cab3812e777efa7d6c3136 100755
--- a/ci/x86_64-linux-debug.sh
+++ b/ci/x86_64-linux-debug.sh
@@ -58,6 +58,7 @@ stage3-debug/bin/zig fmt --check .. \
 stage3-debug/bin/zig build -Dtarget=arm-linux-musleabihf
 
 stage3-debug/bin/zig build test docs \
+  -j1 \
   -fqemu \
   -fwasmtime \
   -Dstatic-llvm \
diff --git a/ci/x86_64-linux-release.sh b/ci/x86_64-linux-release.sh
index cdb24e4a6f9475a7692300d28eb5a57fea5131c3..3305f5e95102e964bb6c77c17ee6ba9cd802e850 100755
--- a/ci/x86_64-linux-release.sh
+++ b/ci/x86_64-linux-release.sh
@@ -59,6 +59,7 @@ stage3-release/bin/zig fmt --check .. \
 stage3-release/bin/zig build -Dtarget=arm-linux-musleabihf
 
 stage3-release/bin/zig build test docs \
+  -j1 \
   -fqemu \
   -fwasmtime \
   -Dstatic-llvm \
diff --git a/ci/x86_64-macos-debug.sh b/ci/x86_64-macos-debug.sh
index c24ff5d29581559e3d4a2fd0493abd54fc089f17..edd35970b881b7765ce8b2eec1ff354e36955dfa 100755
--- a/ci/x86_64-macos-debug.sh
+++ b/ci/x86_64-macos-debug.sh
@@ -48,6 +48,7 @@ cmake .. \
 make $JOBS install
 
 stage3/bin/zig build test docs \
+  -j1 \
   --zig-lib-dir "$(pwd)/../lib" \
   -Denable-macos-sdk \
   -Dstatic-llvm \
diff --git a/ci/x86_64-macos-release.sh b/ci/x86_64-macos-release.sh
index a4dedb4446f16f4a5c66c2133e1471557c892ede..65dea3afcbd7b64d84be74d57cac1d89e2bf22e3 100755
--- a/ci/x86_64-macos-release.sh
+++ b/ci/x86_64-macos-release.sh
@@ -48,6 +48,7 @@ cmake .. \
 make $JOBS install
 
 stage3/bin/zig build test docs \
+  -j1 \
   --zig-lib-dir "$(pwd)/../lib" \
   -Denable-macos-sdk \
   -Dstatic-llvm \
diff --git a/test/tests.zig b/test/tests.zig
index e470a4f251cd1f2464b579dac6305459cad3e2bc..fe2efbc06ea5c4c0751ab0f67ce88754c10a0be7 100644
--- a/test/tests.zig
+++ b/test/tests.zig
@@ -1067,6 +1067,10 @@ pub const StandaloneContext = struct {
         zig_args.append(rel_zig_exe) catch unreachable;
         zig_args.append("build") catch unreachable;
 
+        // TODO: fix the various non-concurrency-safe issues in zig's standalone tests,
+        // and then remove this!
+        zig_args.append("-j1") catch @panic("OOM");
+
         zig_args.append("--build-file") catch unreachable;
         zig_args.append(b.pathFromRoot(build_file)) catch unreachable;