diff --git a/ci/lib-travisci.sh b/ci/lib-travisci.sh
index 331d3eb3a6..348fe3c3c1 100755
--- a/ci/lib-travisci.sh
+++ b/ci/lib-travisci.sh
@@ -22,7 +22,9 @@ skip_branch_tip_with_tag () {
 }
 
 # Set 'exit on error' for all CI scripts to let the caller know that
-# something went wrong
+# something went wrong.
+# Set tracing executed commands, primarily setting environment variables
+# and installing dependencies.
 set -ex
 
 skip_branch_tip_with_tag
diff --git a/ci/print-test-failures.sh b/ci/print-test-failures.sh
index 8c8973cbf3..97cc059019 100755
--- a/ci/print-test-failures.sh
+++ b/ci/print-test-failures.sh
@@ -5,6 +5,9 @@
 
 . ${0%/*}/lib-travisci.sh
 
+# Tracing executed commands would produce too much noise in the loop below.
+set +x
+
 for TEST_EXIT in t/test-results/*.exit
 do
 	if [ "$(cat "$TEST_EXIT")" != "0" ]
diff --git a/ci/run-linux32-build.sh b/ci/run-linux32-build.sh
index e30fb2cddc..a8518eddfb 100755
--- a/ci/run-linux32-build.sh
+++ b/ci/run-linux32-build.sh
@@ -6,6 +6,8 @@
 #   run-linux32-build.sh [host-user-id]
 #
 
+set -x
+
 # Update packages to the latest available versions
 linux32 --32bit i386 sh -c '
     apt update >/dev/null &&
diff --git a/ci/run-windows-build.sh b/ci/run-windows-build.sh
index 8757b3a97c..86999268a7 100755
--- a/ci/run-windows-build.sh
+++ b/ci/run-windows-build.sh
@@ -69,6 +69,10 @@ esac
 
 echo "Visual Studio Team Services Build #${BUILD_ID}"
 
+# Tracing execued commands would produce too much noise in the waiting
+# loop below.
+set +x
+
 # Wait until build job finished
 STATUS=
 RESULT=
@@ -90,6 +94,7 @@ done
 # Print log
 echo ""
 echo ""
+set -x
 gfwci "action=log&buildId=$BUILD_ID" | cut -c 30-
 
 # Set exit code for TravisCI