diff --git a/.github/workflows/regress.yml b/.github/workflows/regress.yml
index 96cee88b4..050acc072 100644
--- a/.github/workflows/regress.yml
+++ b/.github/workflows/regress.yml
@@ -33,7 +33,7 @@ jobs:
           - name: macos-26-arm64
             runner: macos-26
             make: gmake
-            configure: --enable-utf8proc
+            configure: --enable-utf8proc --enable-asan
 
     steps:
       - name: checkout
diff --git a/regress/Makefile b/regress/Makefile
index 6370c77c9..7a4387bd3 100644
--- a/regress/Makefile
+++ b/regress/Makefile
@@ -14,8 +14,7 @@ all:
 		rm -f "$$log"; \
 		printf '%-40s ' "$$test"; \
 		start=$$(date +%s); \
-		ASAN_OPTIONS="abort_on_error=1:detect_leaks=0:$$ASAN_OPTIONS"; \
-		env -i LC_CTYPE=C.UTF-8 ASAN_OPTIONS="$$ASAN_OPTIONS" \
+		env -i LC_CTYPE=C.UTF-8 MallocNanoZone=0 \
 		    sh -x "$$test" >"$$log" 2>&1; \
 		if [ $$? -eq 0 ]; then \
 			end=$$(date +%s); \
diff --git a/regress/format-variables.sh b/regress/format-variables.sh
index 9131c2cf4..449712e34 100644
--- a/regress/format-variables.sh
+++ b/regress/format-variables.sh
@@ -296,7 +296,7 @@ sleep 1
 # write end of a FIFO open, so client_* variables have a client to read.
 rm -f "$FIFO"
 mkfifo "$FIFO" || exit 1
-sleep 30 >"$FIFO" &
+while :; do sleep 1; done >"$FIFO" &
 HOLD=$!
 $TMUX -C attach -t cov <"$FIFO" >/dev/null 2>&1 &
 CC=$!