diff --git a/Makefile.common b/Makefile.common
index d1e17a8..bbf4ff6 100644
--- a/Makefile.common
+++ b/Makefile.common
@@ -205,12 +205,12 @@ bumpnogit:
 
 $(__missingsources): sources
 
-fetch-from-srpm:
-	@tmp=$$(mktemp -d -p "."); \
+# First argument is a Clear Linux build number (e.g. 22000)
+define fetch-from-srpm
+	tmp=$$(mktemp -d -p "."); \
 	srpm=$$(rpmspec --srpm -q --qf "%{NVR}.src.rpm\n" $(SPECFILE)); \
-	if cd "$$tmp" && ! curl -f -L -O $(LATEST_SRPMS)/$$srpm; then \
-		echo "Failed to download $$srpm from latest Clear Linux release." >&2; \
-		echo "Run \"git pull\" and try again." >&2; \
+	if cd "$$tmp" && ! curl -s -S -f -L -O $(DOWNLOAD_MIRROR)/releases/$(1)/clear/source/SRPMS/$$srpm; then \
+		echo "Failed to download $$srpm from Clear Linux release $(1)." >&2; \
 		cd .. && rm -rf "$$tmp"; \
 		exit 1; \
 	fi; \
@@ -218,23 +218,26 @@ fetch-from-srpm:
 	cd ..; \
 	srclist=$$(rpmspec --srpm -q --qf "[%{SOURCE}\n]" $(SPECFILE)); \
 	for s in $$srclist; do \
-		if ! mv "$$tmp"/$$s .; then \
+		if ! mv --no-clobber "$$tmp"/$$s .; then \
 			echo "Missing source file \"$$s\" in $${srpm}." >&2; \
 			rm -rf "$$tmp"; \
 			exit 1; \
 		fi; \
 		echo "Retrieved source file $$s ..."; \
 	done; \
-	rm -rf "$$tmp";
+	rm -rf "$$tmp"
+endef
 
-#help sources: If SOURCES_URL is defined, download required upstream source
-#help files from that location. Otherwise, try to extract source files from the
-#help SRPM in the latest Clear Linux release, as specified by the LATEST_SRPMS
-#help variable. This will run automatically, as a dependency. NOTE: A Koji
-#help server can make use of this "make sources" command, since it lives in a
-#help repo named "common". If you use this makefile in Koji, ensure
-#help "make sources" continues to work for both remote and local builds, since
-#help it is a prerequisite of several commands for building packages.
+#help sources: If SOURCES_URL is defined, download required upstream source files
+#help from that location. Otherwise, try to download source files according to the
+#help URLs listed in the spec file. If any of the source files fail to download,
+#help check for the relevant SRPM from published releases of Clear Linux OS, and
+#help extract the files if found. Note that SRPMs are taken from the DOWNLOAD_MIRROR
+#help location. This will run automatically, as a dependency. NOTE: A Koji server can
+#help make use of this "make sources" command, since it lives in a repo named
+#help "common". If you use this makefile in Koji, ensure "make sources" continues to
+#help work for both remote and local builds, since it is a prerequisite of several
+#help commands for building packages.
 ifneq ($(strip $(SOURCES_URL)),)
 sources: upstream
 	while read u; do \
@@ -250,7 +253,23 @@ sources: upstream
 	done < upstream
 else
 sources:
-	$(MAKE) fetch-from-srpm
+	@$(MAKE) generateupstream; \
+	[ $$? -eq 0 ] && exit 0; \
+	nvr="$$(rpmspec --srpm -q --qf '%{NAME}\t%{VERSION}\t%{RELEASE}\n' $(SPECFILE))"; \
+	latest_builds=$$(git -C $(TOPLVL)/projects/common tag -l | sort -rn); \
+	for b in $$latest_builds; do \
+		url="$(DOWNLOAD_MIRROR)/releases/$$b/clear/source/package-sources"; \
+		echo "Checking for source files in build $$b ..."; \
+		if grep -q "$$nvr" <(curl -s -f -L $$url); then \
+			$(call fetch-from-srpm,$$b); \
+			if [ $$? -eq 0 ]; then \
+				echo "Source files retrieved from build $$b"; \
+				exit 0; \
+			fi; \
+		fi; \
+	done; \
+	echo "Source files not found for package"; \
+	exit 1
 endif
 
 prekoji-checks:
@@ -372,18 +391,20 @@ install:
 #help calculating their hashes. Autospec performs this step automatically, so ignore
 #help it for packages managed with autospec.
 generateupstream:
-	@rm -f upstream
+	@mv upstream upstream.bak
 	@urls=$$(rpmspec -D '_vendor clr' -P $(SPECFILE) | sed -n "s|^Source[0-9]*[[:blank:]]*:[[:blank:]]*\(..*://..*\)$$|\1|p"); \
 	for url in $$urls; do \
 		filename=$$(basename $$url); \
 		if [ ! -e $$filename ]; then \
 			if ! curl --fail -L -O $$url; then \
 				echo "Failed to download $$url"; \
+				mv --no-clobber upstream.bak upstream; \
 				exit 1; \
 			fi; \
 		fi; \
 		echo $$(sha1sum $$filename | cut -d\  -f1)/$$filename >> upstream; \
 	done
+	@rm upstream.bak
 	@cat upstream
 
 #help drop-abandoned: Remove all unused patches from the git tree