diff --git a/dev/tools/phan/config.php b/dev/tools/phan/config.php
index 085d4daba12..178a021e00c 100644
--- a/dev/tools/phan/config.php
+++ b/dev/tools/phan/config.php
@@ -331,6 +331,7 @@ return [
 		// Dolibarr uses a lot of internal deprecated stuff, not reporting
 		'PhanDeprecatedProperty',
 		'PhanDeprecatedFunction',
+		'PhanCompatibleNegativeStringOffset',
 		// Dolibarr has quite a few strange noop assignments like $abc=$abc;
 		'PhanPluginDuplicateExpressionAssignment',
 		// Nulls are likely mostly false positives
diff --git a/dev/tools/phan/config_extended.php b/dev/tools/phan/config_extended.php
index a186b90bd25..65dcc8f7389 100644
--- a/dev/tools/phan/config_extended.php
+++ b/dev/tools/phan/config_extended.php
@@ -326,6 +326,8 @@ return [
 	// Add any issue types (such as 'PhanUndeclaredMethod')
 	// here to inhibit them from being reported
 	'suppress_issue_types' => [
+		'PhanCompatibleNegativeStringOffset',	// return false positive
+
 		'PhanPluginWhitespaceTab',		// Dolibarr used tabs
 		'PhanPluginCanUsePHP71Void',	// Dolibarr is maintaining 7.0 compatibility
 		'PhanPluginShortArray',			// Dolibarr uses array()
@@ -335,6 +337,7 @@ return [
 		'PhanPluginCanUseReturnType',			// Fixer - Report/Add return types in the function definition (function abc(string $var) (adds string)
 		'PhanPluginCanUseNullableParamType',	// Fixer - Report/Add nullable parameter types in the function definition
 		'PhanPluginCanUseNullableReturnType',	// Fixer - Report/Add nullable return types in the function definition
+
 		'PhanPluginNonBoolBranch',			// Not essential - 31240+ occurrences
 		'PhanPluginNumericalComparison',	// Not essential - 19870+ occurrences
 		'PhanTypeMismatchArgument',			// Not essential - 12300+ occurrences