diff --git a/.changelog/5155.txt b/.changelog/5155.txt
new file mode 100644
index 00000000000..24d49feb84a
--- /dev/null
+++ b/.changelog/5155.txt
@@ -0,0 +1,3 @@
+```release-note:bug
+cloudbuild: marked `google_cloudbuild_trigger` as requiring one of branch_name/tag_name/commit_sha  within build.source.repo_source
+```
diff --git a/google/resource_cloudbuild_trigger.go b/google/resource_cloudbuild_trigger.go
index e841ea673b9..c4bfdb89305 100644
--- a/google/resource_cloudbuild_trigger.go
+++ b/google/resource_cloudbuild_trigger.go
@@ -529,11 +529,13 @@ One of 'storageSource' or 'repoSource' must be provided.`,
 													Description: `Regex matching branches to build. Exactly one a of branch name, tag, or commit SHA must be provided.
 The syntax of the regular expressions accepted is the syntax accepted by RE2 and 
 described at https://github.com/google/re2/wiki/Syntax`,
+													ExactlyOneOf: []string{},
 												},
 												"commit_sha": {
-													Type:        schema.TypeString,
-													Optional:    true,
-													Description: `Explicit commit SHA to build. Exactly one a of branch name, tag, or commit SHA must be provided.`,
+													Type:         schema.TypeString,
+													Optional:     true,
+													Description:  `Explicit commit SHA to build. Exactly one a of branch name, tag, or commit SHA must be provided.`,
+													ExactlyOneOf: []string{},
 												},
 												"dir": {
 													Type:     schema.TypeString,
@@ -565,6 +567,7 @@ If omitted, the project ID requesting the build is assumed.`,
 													Description: `Regex matching tags to build. Exactly one a of branch name, tag, or commit SHA must be provided.
 The syntax of the regular expressions accepted is the syntax accepted by RE2 and 
 described at https://github.com/google/re2/wiki/Syntax`,
+													ExactlyOneOf: []string{},
 												},
 											},
 										},