diff --git a/test/shell/test_coverage_equals_in_target.sh b/test/shell/test_coverage_equals_in_target.sh
index 7dbaaa471..2f37fa8e8 100755
--- a/test/shell/test_coverage_equals_in_target.sh
+++ b/test/shell/test_coverage_equals_in_target.sh
@@ -4,6 +4,7 @@ dir=$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )
 . "${dir}"/test_helper.sh
 runner=$(get_test_runner "${1:-local}")
 
+# Default to 2.12.19 for `diff` tests because other versions change the output.
 SCALA_VERSION="${SCALA_VERSION:-2.12.19}"
 
 test_coverage_target_name_contains_equals_sign() {
diff --git a/test/shell/test_coverage_scalatest.sh b/test/shell/test_coverage_scalatest.sh
index e81dbea63..e29b6adc2 100755
--- a/test/shell/test_coverage_scalatest.sh
+++ b/test/shell/test_coverage_scalatest.sh
@@ -4,6 +4,7 @@ dir=$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )
 . "${dir}"/test_helper.sh
 runner=$(get_test_runner "${1:-local}")
 
+# Default to 2.12.19 for `diff` tests because other versions change the output.
 SCALA_VERSION="${SCALA_VERSION:-2.12.19}"
 
 test_coverage_on() {
diff --git a/test/shell/test_coverage_scalatest_resources.sh b/test/shell/test_coverage_scalatest_resources.sh
index cef6e690e..08bb38b74 100755
--- a/test/shell/test_coverage_scalatest_resources.sh
+++ b/test/shell/test_coverage_scalatest_resources.sh
@@ -4,6 +4,7 @@ dir=$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )
 . "${dir}"/test_helper.sh
 runner=$(get_test_runner "${1:-local}")
 
+# Default to 2.12.19 for `diff` tests because other versions change the output.
 SCALA_VERSION="${SCALA_VERSION:-2.12.19}"
 
 test_coverage_succeeds_resource_call() {
@@ -16,7 +17,6 @@ test_coverage_succeeds_resource_call() {
 
 test_coverage_includes_resource_test_targets() {
     bazel coverage \
-        --repo_env="SCALA_VERSION=${SCALA_VERSION}" \
         --instrument_test_targets=True \
         //test/coverage_scalatest_resources/consumer:tests
     grep -q "SF:test/coverage_scalatest_resources/consumer/src/test/scala/com/example/consumer/ConsumerSpec.scala" $(bazel info bazel-testlogs)/test/coverage_scalatest_resources/consumer/tests/coverage.dat
diff --git a/test/shell/test_coverage_specs2_with_junit.sh b/test/shell/test_coverage_specs2_with_junit.sh
index f962a00f1..725eecccd 100755
--- a/test/shell/test_coverage_specs2_with_junit.sh
+++ b/test/shell/test_coverage_specs2_with_junit.sh
@@ -4,6 +4,7 @@ dir=$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )
 . "${dir}"/test_helper.sh
 runner=$(get_test_runner "${1:-local}")
 
+# Default to 2.12.19 for `diff` tests because other versions change the output.
 SCALA_VERSION="${SCALA_VERSION:-2.12.19}"
 
 test_coverage_on() {
@@ -15,7 +16,6 @@ test_coverage_on() {
 
 test_coverage_includes_test_targets() {
     bazel coverage \
-        --repo_env="SCALA_VERSION=${SCALA_VERSION}" \
         --instrument_test_targets=True \
         //test/coverage_specs2_with_junit:test-specs2-with-junit
     grep -q "SF:test/coverage_specs2_with_junit/TestWithSpecs2WithJUnit.scala" $(bazel info bazel-testlogs)/test/coverage_specs2_with_junit/test-specs2-with-junit/coverage.dat