diff --git a/composer.json b/composer.json
index a0eff1b..d077212 100644
--- a/composer.json
+++ b/composer.json
@@ -45,7 +45,7 @@
         "amphp/phpunit-util": "^3",
         "amphp/php-cs-fixer-config": "^2",
         "amphp/process": "^2",
-        "psalm/phar": "^5.4"
+        "psalm/phar": "5.20"
     },
     "autoload": {
         "psr-4": {
diff --git a/psalm.xml b/psalm.xml
index b517acc..66986e5 100644
--- a/psalm.xml
+++ b/psalm.xml
@@ -39,6 +39,12 @@
             </errorLevel>
         </MissingClosureReturnType>
 
+        <RiskyTruthyFalsyComparison>
+            <errorLevel type="suppress">
+                <directory name="src"/>
+            </errorLevel>
+        </RiskyTruthyFalsyComparison>
+
         <UnsupportedPropertyReferenceUsage>
             <errorLevel type="suppress">
                 <directory name="src"/>