diff --git a/Makefile b/Makefile
index cd7e456..16ac525 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
 LAST_COMMIT := $(shell git rev-parse --short HEAD)
 LAST_COMMIT_DATE := $(shell git show -s --format=%ci ${LAST_COMMIT})
 VERSION := $(shell git describe)
-BUILDSTR := ${VERSION} (${LAST_COMMIT} $(shell date -u +"%Y-%m-%dT%H:%M:%SZ"))
+BUILDSTR := ${VERSION} (${LAST_COMMIT} $(shell date -u +"%Y-%m-%dT%H:%M:%S%z"))
 
 BIN := listmonk
 STATIC := config.toml.sample schema.sql queries.sql public email-templates frontend/build:/frontend