diff --git a/platform/base/change/github/change_id.go b/platform/base/change/github/change_id.go
index d6e75f465..b79341066 100644
--- a/platform/base/change/github/change_id.go
+++ b/platform/base/change/github/change_id.go
@@ -109,15 +109,26 @@ func ParseChangeID(raw string) (ChangeID, error) {
 	}
 
 	prNumber, err := strconv.Atoi(prStr)
+
 	if err != nil {
 		return ChangeID{}, fmt.Errorf("invalid change ID %q: PR number %q is not a valid integer (expected format: %s)", raw, prStr, changeIDFormat)
 	}
 
+	if prNumber < 1 || strconv.Itoa(prNumber) != prStr {
+		return ChangeID{}, fmt.Errorf("invalid change ID %q: PR number %q must be a positive integer without sign or leading zeros (expected format: %s)", raw, prStr, changeIDFormat)
+	}
+
 	// Split repo path: last segment is repo name, everything before is the owner.
 	if len(repoSegments) < 2 {
 		return ChangeID{}, fmt.Errorf("invalid change ID %q: repo path must have at least owner/repo (expected format: %s)", raw, changeIDFormat)
 	}
 
+	for _, seg := range repoSegments {
+		if seg == "" {
+			return ChangeID{}, fmt.Errorf("invalid change ID %q: repo path contains an empty segment (expected format: %s)", raw, changeIDFormat)
+		}
+	}
+
 	repo := repoSegments[len(repoSegments)-1]
 	org := strings.Join(repoSegments[:len(repoSegments)-1], "/")
 
diff --git a/platform/base/change/github/change_id_test.go b/platform/base/change/github/change_id_test.go
index 58d7a2471..009f9a531 100644
--- a/platform/base/change/github/change_id_test.go
+++ b/platform/base/change/github/change_id_test.go
@@ -133,6 +133,31 @@ func TestParseChangeID(t *testing.T) {
 			raw:     "github://github.example.com/uber/submitqueue/pull/abc/" + shaAFull,
 			wantErr: true,
 		},
+		{
+			name:    "zero PR number",
+			raw:     "github://github.example.com/uber/submitqueue/pull/0/" + shaAFull,
+			wantErr: true,
+		},
+		{
+			name:    "negative PR number",
+			raw:     "github://github.example.com/uber/submitqueue/pull/-3/" + shaAFull,
+			wantErr: true,
+		},
+		{
+			name:    "plus-signed PR number",
+			raw:     "github://github.example.com/uber/submitqueue/pull/+5/" + shaAFull,
+			wantErr: true,
+		},
+		{
+			name:    "leading-zero PR number",
+			raw:     "github://github.example.com/uber/submitqueue/pull/007/" + shaAFull,
+			wantErr: true,
+		},
+		{
+			name:    "empty interior org segment",
+			raw:     "github://github.example.com/uber//frontend/webapp/pull/42/" + shaAFull,
+			wantErr: true,
+		},
 		{
 			name:    "empty SHA",
 			raw:     "github://github.example.com/uber/submitqueue/pull/123/",