diff --git a/renderdoc/3rdparty/compressonator/BC7_Encode_Kernel.cpp b/renderdoc/3rdparty/compressonator/BC7_Encode_Kernel.cpp
index 67a8685fb..0f15688a7 100644
--- a/renderdoc/3rdparty/compressonator/BC7_Encode_Kernel.cpp
+++ b/renderdoc/3rdparty/compressonator/BC7_Encode_Kernel.cpp
@@ -1156,7 +1156,7 @@ void  GetProjectedIndex(
     CGV_IMAGE img_diff = image_max-image_min;
 
     if (img_diff == 0.0f) return;
-    if (isnan(img_diff)) return;
+    if (std::isnan(img_diff)) return;
 
     image_s = (clusters-1)/img_diff;