diff --git a/.github/workflows/builds.yml b/.github/workflows/builds.yml
index 06e5bf5d61..c80516fe7f 100644
--- a/.github/workflows/builds.yml
+++ b/.github/workflows/builds.yml
@@ -1336,6 +1336,10 @@ jobs:
       - run: make install-headers
       - run: make install-library
 
+      - run: TZ="UTC" ./src/suricata -u -U LogCustomFormatTest01
+      - run: TZ="Brazil/East" ./src/suricata -u -U LogCustomFormatTest01
+      - run: TZ="Saskatchewan/Regina" ./src/suricata -u -U LogCustomFormatTest01
+
   ubuntu-24-04-rust-vars:
     name: Ubuntu 24.04 (RUSTC+CARGO vars)
     runs-on: ubuntu-latest
diff --git a/src/log-cf-common.c b/src/log-cf-common.c
index 4d1c48b706..b1f504632f 100644
--- a/src/log-cf-common.c
+++ b/src/log-cf-common.c
@@ -245,7 +245,7 @@ static int LogCustomFormatTest01(void)
     tm.tm_year = 114;
     tm.tm_wday = 1;
     tm.tm_yday = 13;
-    tm.tm_isdst = 0;
+    tm.tm_isdst = -1;
     SCTime_t ts = SCTIME_FROM_SECS(mktime(&tm));
 
     MemBuffer *buffer = MemBufferCreateNew(62);