diff --git a/.github/workflows/linux_tests.yaml b/.github/workflows/linux_tests.yaml
index 18b89a99b..b02bfd149 100644
--- a/.github/workflows/linux_tests.yaml
+++ b/.github/workflows/linux_tests.yaml
@@ -436,9 +436,9 @@ jobs:
           # libtclenvmodules build requirements
           sudo apt-get install -y gcc autoconf
           # manually install tcl9.1
-          curl -L --output tcl9.1a1-src.tar.gz http://downloads.sourceforge.net/tcl/tcl9.1a1-src.tar.gz
-          tar xfz tcl9.1a1-src.tar.gz
-          cd tcl9.1a1/unix
+          curl -L --output tcl9.1b0-src.tar.gz http://downloads.sourceforge.net/tcl/tcl9.1b0-src.tar.gz
+          tar xfz tcl9.1b0-src.tar.gz
+          cd tcl9.1b0/unix
           ./configure
           make -j
           sudo make install
diff --git a/testsuite/config/unix.exp b/testsuite/config/unix.exp
index 58d04c1f8..c31571a21 100644
--- a/testsuite/config/unix.exp
+++ b/testsuite/config/unix.exp
@@ -29,6 +29,16 @@
 # Tcl>=8.6): use channel pipe instead of saving these outputs in file
 if {[lindex [lsort -dictionary [list 8.6 [info tclversion]]] 1] eq [info tclversion]} {
 
+# catch background errors, like a modulecmd process killed by a signal that
+# makes readpipe raise an uncaught CHILDKILLED error from its event handler.
+# without this catching procedure defined, such an error leaves the endpipe
+# variable unset and the vwait call in modulecmd_xxx_ hangs forever
+proc bgerror {msg} {
+    send_user "ERROR: background error caught: $msg\n"
+    # release ongoing command wait to make related test fail right away
+    set ::endpipe error
+}
+
 proc readpipe {p1 p2 varname {exit_varname {}}} {
     append ::$varname [read $p1]
     if {[eof $p1]} {