Index: tcl/build.sh
==================================================================
--- tcl/build.sh
+++ tcl/build.sh
@@ -35,11 +35,11 @@
 			FOSSILTAG="trunk"
 		fi
 	elif echo "${TCLVERS}" | grep '^fossil_' >/dev/null; then
 		use_fossil='1'
 
-		FOSSILTAG=$(echo "${TCLVERS}" | sed 's/^fossil_//g')
+		FOSSILTAG=$(echo "${TCLVERS}" | sed 's/^fossil_//g;s/_tk=.*$//g')
 	fi
 	export FOSSILTAG
 
 	if [ -d 'buildsrc' ]; then
 		# Override here to avoid downloading tarball from Fossil if we

Index: tk/build.sh
==================================================================
--- tk/build.sh
+++ tk/build.sh
@@ -47,11 +47,15 @@
 			FOSSILTAG="trunk"
 		fi
 	elif echo "${TCLVERS}" | grep '^fossil_' >/dev/null; then
 		use_fossil='1'
 
-		FOSSILTAG=$(echo "${TCLVERS}" | sed 's/^fossil_//g')
+		if echo "${TCLVERS}" | grep '^fossil_.*_tk=' >/dev/null; then
+			FOSSILTAG=$(echo "${TCLVERS}" | sed 's/^fossil_.*_tk=//g')
+		else
+			FOSSILTAG=$(echo "${TCLVERS}" | sed 's/^fossil_//g')
+		fi
 	fi
 
 	if [ -d 'buildsrc' ]; then
 		# Override here to avoid downloading tarball from Fossil if we
 		# have a particular tree already available.