diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index ff0777a3..917066b4 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -14,8 +14,8 @@ jobs:
     strategy:
       matrix:
         valgrind:
-           - { configure: ''                  , make: 'check' }
-           - { configure: '--enable-valgrind' , make: 'check-valgrind'  }
+           - { configure: ''                  , cflags: '',    make: 'check' }
+           - { configure: '--enable-valgrind' , cflags: '-O2', make: 'check-valgrind'  }
         options:
            - { configure: ''                    }
            - { configure: '--without-libxml2'   }
@@ -35,7 +35,7 @@ jobs:
       - name: Build the library
         run: |
           ./bootstrap.sh
-          ./configure ${{ matrix.options.configure }} ${{ matrix.valgrind.configure }} CFLAGS="-Werror -g3"
+          ./configure ${{ matrix.options.configure }} ${{ matrix.valgrind.configure }} CFLAGS="-Werror -g3 ${{ matrix.valgrind.cflags }}"
           make -j$(nproc)
       - name: Run tests
         run: |
@@ -135,6 +135,11 @@ jobs:
         if: ${{ !failure() }}
         run: |
           cat testbuild.log
+      - name: Error logs
+        if: ${{ failure() }}
+        run: |
+          cat testbuild.log || true
+          cat testerr.log || true
 
   code-style:
     runs-on: ubuntu-20.04
diff --git a/.gitignore b/.gitignore
index 8b39b998..3d309496 100644
--- a/.gitignore
+++ b/.gitignore
@@ -46,6 +46,7 @@ examples/roster
 examples/uuid
 examples/vcard
 testbuild*.log
+testerr*.log
 test-release/
 test_stamp
 test-suite*.log
diff --git a/Makefile.am b/Makefile.am
index 394ac065..f918c979 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -333,6 +333,7 @@ dist-archives:
 
 test-release: dist
 	@touch testbuild-$(PACKAGE_VERSION).log && ln -sf testbuild-$(PACKAGE_VERSION).log testbuild.log
+	@touch testerr-$(PACKAGE_VERSION).log && ln -sf testerr-$(PACKAGE_VERSION).log testerr.log
 	@mkdir -p test-release && cp $(PACKAGE_TARNAME)-$(PACKAGE_VERSION).tar.* test-release && pushd test-release && \
 		tar xzf $(PACKAGE_TARNAME)-$(PACKAGE_VERSION).tar.gz  && pushd $(PACKAGE_TARNAME)-$(PACKAGE_VERSION) && ./testbuild.sh && popd && rm -rf $(PACKAGE_TARNAME)-$(PACKAGE_VERSION) && \
 		echo "Success" && popd
diff --git a/testbuild.sh b/testbuild.sh
index 16ec4285..be53be43 100755
--- a/testbuild.sh
+++ b/testbuild.sh
@@ -1,6 +1,7 @@
 #!/bin/sh
 
 logfile="../../testbuild.log"
+errfile="../../testerr.log"
 
 err_out() {
   tail $logfile
@@ -8,6 +9,6 @@ err_out() {
 }
 
 ./bootstrap.sh
-./configure >> $logfile || err_out
-make -j$(( `nproc` * 2 + 1 )) >> $logfile || err_out
-make check >> $logfile || err_out
+./configure >> $logfile 2>> $errfile || err_out
+make -j$(( `nproc` * 2 + 1 )) >> $logfile 2>> $errfile || err_out
+make check >> $logfile 2>> $errfile || err_out
diff --git a/tests/test_serialize_sm.c b/tests/test_serialize_sm.c
index 8088ef30..ce4846a1 100644
--- a/tests/test_serialize_sm.c
+++ b/tests/test_serialize_sm.c
@@ -147,6 +147,7 @@ int main()
     conn->intf = intf;
     state = conn->state;
     conn->state = XMPP_STATE_CONNECTED;
+    conn->sock = 123;
 
     xmpp_send_raw(conn, "foo", 3);
     ENSURE_EQ(xmpp_conn_send_queue_len(conn), 1);