diff --git a/src/__tests__/index.js b/src/__tests__/index.js
index cae4e30..2361fb0 100644
--- a/src/__tests__/index.js
+++ b/src/__tests__/index.js
@@ -368,17 +368,31 @@ test(
 );
 
 test(
-  'should skip constant()',
+  'should skip constant function',
   testValue,
   'calc(constant(safe-area-inset-left))',
-  'constant(safe-area-inset-left)',
+  'calc(constant(safe-area-inset-left))',
 );
 
 test(
-  'should skip env()',
+  'should skip env function',
   testValue,
   'calc(env(safe-area-inset-left))',
-  'env(safe-area-inset-left)',
+  'calc(env(safe-area-inset-left))',
+);
+
+test(
+  'should skip env function (#1)',
+  testValue,
+  'calc(env(safe-area-inset-left, 50px 20px))',
+  'calc(env(safe-area-inset-left, 50px 20px))',
+);
+
+test(
+  'should skip unknown function',
+  testValue,
+  'calc(unknown(safe-area-inset-left))',
+  'calc(unknown(safe-area-inset-left))',
 );
 
 test(
diff --git a/src/lib/stringifier.js b/src/lib/stringifier.js
index d8e1bff..40f92f5 100644
--- a/src/lib/stringifier.js
+++ b/src/lib/stringifier.js
@@ -54,9 +54,7 @@ export default function (
   ) {
   let str = stringify(node, options.precision);
 
-  const shouldPrintCalc =
-    node.type === "MathExpression" ||
-    (node.type === "Function" && node.value.toLowerCase().slice(0, 4) === "var(");
+  const shouldPrintCalc = node.type === "MathExpression" || node.type === "Function";
 
   if (shouldPrintCalc) {
     // if calc expression couldn't be resolved to a single value, re-wrap it as