diff --git a/.github/workflows/bundle.yml b/.github/workflows/bundle.yml
index 8a1f785..439fbb7 100644
--- a/.github/workflows/bundle.yml
+++ b/.github/workflows/bundle.yml
@@ -12,7 +12,7 @@ jobs:
       - name: Create bundles
         run: |
           ./create_bundles_in_container.sh
-          sha512sum *.tar.gz *.tar.xz > SHA512SUMS
+          sha512sum *.tar.gz *.tar.xz | tee SHA512SUMS
 
       - name: Upload bundles
         uses: actions/upload-artifact@v3
diff --git a/Makefile b/Makefile
index 2ff5518..9389d7b 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,7 @@
 VERSION := $(shell rpm --specfile *.spec --qf '%{VERSION}\n' | head -1)
 RELEASE := $(shell rpm --specfile *.spec --qf '%{RELEASE}\n' | head -1 | cut -d. -f1)
 CHANGELOGTIME := $(shell rpm --specfile *.spec --qf '%{CHANGELOGTIME}\n' | head -1)
+SOURCE_DATE_EPOCH := $(shell echo $$(( $(CHANGELOGTIME) - $(CHANGELOGTIME) % 86400 )))
 
 NAME       := grafana
 RPM_NAME   := $(NAME)
@@ -62,7 +63,7 @@ $(VENDOR_TAR): $(SOURCE_TAR)
 	# Create tarball
 	XZ_OPT=-9 tar \
 		--sort=name \
-		--mtime="@$(CHANGELOGTIME)" \
+		--mtime="@$(SOURCE_DATE_EPOCH)" --clamp-mtime \
 		--owner=0 --group=0 --numeric-owner \
 		-cJf $@ \
 		$(SOURCE_DIR)/vendor \
@@ -84,7 +85,7 @@ $(WEBPACK_TAR): $(VENDOR_TAR)
 	# Create tarball
 	tar \
 		--sort=name \
-		--mtime="@$(CHANGELOGTIME)" \
+		--mtime="@$(SOURCE_DATE_EPOCH)" --clamp-mtime \
 		--owner=0 --group=0 --numeric-owner \
 		-czf $@ \
 		$(SOURCE_DIR)/public/build \
diff --git a/grafana.spec b/grafana.spec
index 4679bd6..489313f 100644
--- a/grafana.spec
+++ b/grafana.spec
@@ -30,7 +30,7 @@ end}
 
 Name:             grafana
 Version:          7.5.15
-Release:          1%{?dist}
+Release:          2%{?dist}
 Summary:          Metrics dashboard and graph editor
 License:          ASL 2.0
 URL:              https://grafana.org
@@ -41,13 +41,13 @@ Source0:          https://github.com/grafana/grafana/archive/v%{version}/%{name}
 # Source1 contains the bundled Go and Node.js dependencies
 # Note: In case there were no changes to this tarball, the NVR of this tarball
 # lags behind the NVR of this package.
-Source1:          grafana-vendor-%{version}-1.tar.xz
+Source1:          grafana-vendor-%{version}-2.tar.xz
 
 %if %{compile_frontend} == 0
 # Source2 contains the precompiled frontend
 # Note: In case there were no changes to this tarball, the NVR of this tarball
 # lags behind the NVR of this package.
-Source2:          grafana-webpack-%{version}-1.tar.gz
+Source2:          grafana-webpack-%{version}-2.tar.gz
 %endif
 
 # Source3 contains Grafana configuration defaults for distributions
@@ -972,6 +972,11 @@ OPENSSL_FORCE_FIPS_MODE=1 GOLANG_FIPS=1 go test -v ./pkg/util -run TestEncryptio
 
 
 %changelog
+* Mon Apr 11 2022 Andreas Gerstmayr <agerstmayr@redhat.com> 7.5.15-2
+- use clamp-mtime when generating the vendor and webpack tarballs,
+  to preserve past timestamps but still keep reproducibility
+- round tarball mtime timestamp to midnight, to match SOURCE_DATE_EPOCH
+
 * Fri Apr 08 2022 Andreas Gerstmayr <agerstmayr@redhat.com> 7.5.15-1
 - update to 7.5.15 tagged upstream community sources, see CHANGELOG
 - resolve CVE-2022-21673 grafana: Forward OAuth Identity Token can allow users to access some data sources
diff --git a/sources b/sources
index 7d229e6..41bdaba 100644
--- a/sources
+++ b/sources
@@ -1,3 +1,3 @@
 SHA512 (grafana-7.5.15.tar.gz) = cce12e40fd63f9b4c6f3604daa730baa02b47b6a452c34c0a182d581791847ba4ad4644668bcf309d38b104409745677d6863d821f4d5e4f275750e8af525c13
-SHA512 (grafana-webpack-7.5.15-1.tar.gz) = caa79dc5d14df069cb470d205b73f5826746e264569aad24397baaa0a27767242e3bfc9ad588bd1ee3af0327c22faf7b878e21884a4dfed82c832c2c354a0c21
-SHA512 (grafana-vendor-7.5.15-1.tar.xz) = 352e594612b5fbd10189bff90f58dc4ee1d9366319f6273f946ae9502dd7194b272e4a25f611df02e6724348aeb0398d18583786c6658249595d949b98ed3179
+SHA512 (grafana-webpack-7.5.15-2.tar.gz) = ea424a699a60b02776bc59c349e3e4cecf12ce9ea554bbae45afa55ab5235e442fde6e690b8a455bf6ff63bb557bf7c5a412ceb32f70bc94cf9e3e68c4e08840
+SHA512 (grafana-vendor-7.5.15-2.tar.xz) = 32d08620e7ebfa4e53a1877f0fcfddb6e006cf9fad725332f215f658127d45dc0b3987352cb7373c84ce7165c33a392ea631b1373491dc09a9a3d0cd5e2ce439