diff --git a/ci/affects-files.sh b/ci/affects-files.sh
index 6657266768..5fad922593 100755
--- a/ci/affects-files.sh
+++ b/ci/affects-files.sh
@@ -3,23 +3,26 @@
 # Checks if a CI build affects one or more path patterns.  Each command-line
 # argument is checked in series.
 #
-# Bash regular expresses are permitted in the pattern, and the colon (':')
-# character is guaranteed to appear before and after each affected file (and thus
-# can be used as an anchor), eg:
-#     .rs:    -- any file or directory ending in .rs
-#     .rs     -- also matches foo.rs.bar
-#     :snap/  -- anything under the snap/ subdirectory
-#     snap/   -- also matches foo/snap/
+# Bash regular expressions are permitted in the pattern:
+#     ./affects-files.sh .rs$    -- any file or directory ending in .rs
+#     ./affects-files.sh .rs     -- also matches foo.rs.bar
+#     ./affects-files.sh ^snap/  -- anything under the snap/ subdirectory
+#     ./affects-files.sh snap/   -- also matches foo/snap/
 #
+set -e
+cd "$(dirname "$0")"/..
 
 if ci/is-pr.sh; then
   affectedFiles="$(buildkite-agent meta-data get affected_files)"
   echo "Affected files in this PR: $affectedFiles"
 
+  IFS=':' read -ra files <<< "$affectedFiles"
   for pattern in "$@"; do
-    if [[ ":$affectedFiles:" =~ $pattern ]]; then
-      exit 0
-    fi
+    for file in "${files[@]}"; do
+      if [[ $file =~ $pattern ]]; then
+        exit 0
+      fi
+    done
   done
 
   exit 1
diff --git a/ci/pr-snap.sh b/ci/pr-snap.sh
index 41aff8acdf..7d7c0ef262 100755
--- a/ci/pr-snap.sh
+++ b/ci/pr-snap.sh
@@ -1,12 +1,11 @@
 #!/usr/bin/env bash
-set -e
 #
 # Only run snap.sh for pull requests that modify files under /snap
 #
-
+set -e
 cd "$(dirname "$0")"/..
 
-ci/affects-files.sh :snap/ || {
+ci/affects-files.sh ^snap/ || {
   echo "Skipping snap build as no files under /snap were modified"
   exit 0
 }
diff --git a/ci/test-bench.sh b/ci/test-bench.sh
index 908bc60c01..771186716d 100755
--- a/ci/test-bench.sh
+++ b/ci/test-bench.sh
@@ -1,6 +1,5 @@
 #!/usr/bin/env bash
 set -e
-
 cd "$(dirname "$0")/.."
 
 annotate() {
@@ -10,10 +9,10 @@ annotate() {
 }
 
 ci/affects-files.sh \
-  .rs: \
-  ci/test-bench.sh: \
+  .rs$ \
+  ci/test-bench.sh \
 || {
-  annotate --style info --context coverage-info \
+  annotate --style info --context test-bench \
     "Bench skipped as no .rs files were modified"
   exit 0
 }
diff --git a/ci/test-coverage.sh b/ci/test-coverage.sh
index 7545dc41a2..ddf1b3a923 100755
--- a/ci/test-coverage.sh
+++ b/ci/test-coverage.sh
@@ -1,6 +1,5 @@
 #!/usr/bin/env bash
 set -e
-
 cd "$(dirname "$0")/.."
 
 annotate() {
@@ -10,11 +9,11 @@ annotate() {
 }
 
 ci/affects-files.sh \
-  .rs: \
-  ci/test-coverage.sh: \
-  scripts/coverage.sh: \
+  .rs$ \
+  ci/test-coverage.sh \
+  scripts/coverage.sh \
 || {
-  annotate --style info --context coverage-info \
+  annotate --style info --context test-coverage \
     "Coverage skipped as no .rs files were modified"
   exit 0
 }