diff --git a/README.md b/README.md
index fcf18b8..99531f1 100644
--- a/README.md
+++ b/README.md
@@ -12,6 +12,11 @@ cmake (3.x or up)
 *linux build instructions*
 
 ```
+# must be clang 10 or up
+export CC=/usr/bin/clang
+export CXX=/usr/bin/clang++
+
+# clone and build
 git clone https://githacks.org/vmp3/vmprofiler
 cd vmprofiler
 cmake -B build