diff --git a/orx-shader-phrases/src/main/kotlin/ShaderPreprocessor.kt b/orx-shader-phrases/src/main/kotlin/ShaderPreprocessor.kt
index 26e547f1..d282ae6c 100644
--- a/orx-shader-phrases/src/main/kotlin/ShaderPreprocessor.kt
+++ b/orx-shader-phrases/src/main/kotlin/ShaderPreprocessor.kt
@@ -73,6 +73,6 @@ fun preprocessShader(source: String, symbols: Set<String> = emptySet()): String
  * @param url url pointing to GLSL shader source
  * @return GLSL source code with injected shader phrases
  */
-fun preprocessShaderFromUrl(url: String, symbols: Set<String>): String {
+fun preprocessShaderFromUrl(url: String, symbols: Set<String> = emptySet()): String {
     return preprocessShader(codeFromURL(url), symbols)
 }
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