diff --git a/INSTALL.md b/INSTALL.md
index f27cb475..f5cbc184 100644
--- a/INSTALL.md
+++ b/INSTALL.md
@@ -142,6 +142,10 @@ optimization.
 In addition to being faster, PGO builds also tend to be smaller than
 regular `-O3` builds.
 
+**Note**: if you are packaging foot, you should probably remove
+`-march=native`, as that may cause gcc/clang to emit instructions that
+may not be available on other computers.
+
 
 #### Size optimized
 
@@ -186,7 +190,10 @@ later have a regression where PGO with `-O2` is **much** slower.
 If you are using Clang instead of GCC, use the following `CFLAGS` instead:
 
 ```sh
-export CFLAGS="$CFLAGS -O3 -march=native -Wno-ignored-optimization-argument -Wno-profile-instr-out-of-date"
+export CFLAGS="$CFLAGS -O3 -march=native \
+    -Wno-ignored-optimization-argument \
+    -Wno-profile-instr-out-of-date \
+    -Wno-profile-instr-unprofiled"
 ```
 
 Then, tell meson we want to _generate_ profiling data, and build: