diff --git a/ruby/ql/lib/codeql/ruby/security/CommandInjectionCustomizations.qll b/ruby/ql/lib/codeql/ruby/security/CommandInjectionCustomizations.qll
index b1001b372e2..479907d2052 100644
--- a/ruby/ql/lib/codeql/ruby/security/CommandInjectionCustomizations.qll
+++ b/ruby/ql/lib/codeql/ruby/security/CommandInjectionCustomizations.qll
@@ -42,6 +42,16 @@ module CommandInjection {
     SystemCommandExecutionSink() { exists(SystemCommandExecution c | c.isShellInterpreted(this)) }
   }
 
+  /**
+   * A call to `String#shellescape` sanitizes its input.
+   */
+  class ShellwordsEscapeAsSanitizer extends Sanitizer {
+    ShellwordsEscapeAsSanitizer() {
+      // The `Shellwords.shellescape` method is also added as `String#shellescape`.
+      this.(DataFlow::CallNode).getMethodName() = "shellescape"
+    }
+  }
+
   private class ExternalCommandInjectionSink extends Sink {
     ExternalCommandInjectionSink() { ModelOutput::sinkNode(this, "command-injection") }
   }
diff --git a/ruby/ql/test/query-tests/security/cwe-078/CommandInjection/CommandInjection.expected b/ruby/ql/test/query-tests/security/cwe-078/CommandInjection/CommandInjection.expected
index 34d75aa6431..2173fed576a 100644
--- a/ruby/ql/test/query-tests/security/cwe-078/CommandInjection/CommandInjection.expected
+++ b/ruby/ql/test/query-tests/security/cwe-078/CommandInjection/CommandInjection.expected
@@ -13,7 +13,6 @@
 | CommandInjection.rb:83:14:83:34 | "echo #{...}" | CommandInjection.rb:82:23:82:33 | blah_number | CommandInjection.rb:83:14:83:34 | "echo #{...}" | This command depends on a $@. | CommandInjection.rb:82:23:82:33 | blah_number | user-provided value |
 | CommandInjection.rb:92:14:92:39 | "echo #{...}" | CommandInjection.rb:92:22:92:37 | ...[...] | CommandInjection.rb:92:14:92:39 | "echo #{...}" | This command depends on a $@. | CommandInjection.rb:92:22:92:37 | ...[...] | user-provided value |
 | CommandInjection.rb:105:16:105:28 | "cat #{...}" | CommandInjection.rb:104:16:104:21 | call to params | CommandInjection.rb:105:16:105:28 | "cat #{...}" | This command depends on a $@. | CommandInjection.rb:104:16:104:21 | call to params | user-provided value |
-| CommandInjection.rb:107:16:107:40 | "cat #{...}" | CommandInjection.rb:104:16:104:21 | call to params | CommandInjection.rb:107:16:107:40 | "cat #{...}" | This command depends on a $@. | CommandInjection.rb:104:16:104:21 | call to params | user-provided value |
 | CommandInjection.rb:112:33:112:44 | ...[...] | CommandInjection.rb:112:33:112:38 | call to params | CommandInjection.rb:112:33:112:44 | ...[...] | This command depends on a $@. | CommandInjection.rb:112:33:112:38 | call to params | user-provided value |
 | CommandInjection.rb:114:41:114:56 | "#{...}" | CommandInjection.rb:114:44:114:49 | call to params | CommandInjection.rb:114:41:114:56 | "#{...}" | This command depends on a $@. | CommandInjection.rb:114:44:114:49 | call to params | user-provided value |
 edges
@@ -37,11 +36,8 @@ edges
 | CommandInjection.rb:82:23:82:33 | blah_number | CommandInjection.rb:83:14:83:34 | "echo #{...}" | provenance | AdditionalTaintStep |
 | CommandInjection.rb:92:22:92:37 | ...[...] | CommandInjection.rb:92:14:92:39 | "echo #{...}" | provenance | AdditionalTaintStep |
 | CommandInjection.rb:104:9:104:12 | file | CommandInjection.rb:105:16:105:28 | "cat #{...}" | provenance | AdditionalTaintStep |
-| CommandInjection.rb:104:9:104:12 | file | CommandInjection.rb:107:23:107:26 | file | provenance |  |
 | CommandInjection.rb:104:16:104:21 | call to params | CommandInjection.rb:104:16:104:28 | ...[...] | provenance |  |
 | CommandInjection.rb:104:16:104:28 | ...[...] | CommandInjection.rb:104:9:104:12 | file | provenance |  |
-| CommandInjection.rb:107:23:107:26 | file | CommandInjection.rb:107:23:107:38 | call to shellescape | provenance |  |
-| CommandInjection.rb:107:23:107:38 | call to shellescape | CommandInjection.rb:107:16:107:40 | "cat #{...}" | provenance | AdditionalTaintStep |
 | CommandInjection.rb:112:33:112:38 | call to params | CommandInjection.rb:112:33:112:44 | ...[...] | provenance | Sink:MaD:1 |
 | CommandInjection.rb:114:44:114:49 | call to params | CommandInjection.rb:114:44:114:54 | ...[...] | provenance |  |
 | CommandInjection.rb:114:44:114:54 | ...[...] | CommandInjection.rb:114:41:114:56 | "#{...}" | provenance | AdditionalTaintStep Sink:MaD:2 |
@@ -78,14 +74,9 @@ nodes
 | CommandInjection.rb:104:16:104:21 | call to params | semmle.label | call to params |
 | CommandInjection.rb:104:16:104:28 | ...[...] | semmle.label | ...[...] |
 | CommandInjection.rb:105:16:105:28 | "cat #{...}" | semmle.label | "cat #{...}" |
-| CommandInjection.rb:107:16:107:40 | "cat #{...}" | semmle.label | "cat #{...}" |
-| CommandInjection.rb:107:23:107:26 | file | semmle.label | file |
-| CommandInjection.rb:107:23:107:38 | call to shellescape | semmle.label | call to shellescape |
 | CommandInjection.rb:112:33:112:38 | call to params | semmle.label | call to params |
 | CommandInjection.rb:112:33:112:44 | ...[...] | semmle.label | ...[...] |
 | CommandInjection.rb:114:41:114:56 | "#{...}" | semmle.label | "#{...}" |
 | CommandInjection.rb:114:44:114:49 | call to params | semmle.label | call to params |
 | CommandInjection.rb:114:44:114:54 | ...[...] | semmle.label | ...[...] |
 subpaths
-testFailures
-| CommandInjection.rb:107:16:107:40 | "cat #{...}" | Unexpected result: Alert |