diff --git a/docs/Changelog.md b/docs/Changelog.md
index e8b95604e368786a1d67dd0ce408de7e988c2ad7..c488b84ed66d96686c08d48705e1f9ed1ae3d6b2 100644
--- a/docs/Changelog.md
+++ b/docs/Changelog.md
@@ -22,6 +22,7 @@ sending a mail to <afl-users+subscribe@googlegroups.com>.
      - changed execs_per_sec in fuzzer_stats from "current" execs per second
        (which is pointless) to total execs per second
      - bugfix for dictionary insert stage count (fix via Google repo PR)
+  - llvm_mode InsTrim: no pointless instrumentation of 1 block functions
   - afl-clang-fast:
      - show in the help output for which llvm version it was compiled for
      - now does not need to be recompiled between trace-pc and pass
diff --git a/llvm_mode/LLVMInsTrim.so.cc b/llvm_mode/LLVMInsTrim.so.cc
index 995a72173a2dcc5ad573a69290c9f0075f71e847..08d3f68f88acb974f62031f32ebdbbdd732db701 100644
--- a/llvm_mode/LLVMInsTrim.so.cc
+++ b/llvm_mode/LLVMInsTrim.so.cc
@@ -175,7 +175,8 @@ struct InsTrim : public ModulePass {
 
     for (Function &F : M) {
 
-      if (!F.size()) { continue; }
+      // if it is external or only contains one basic block: skip it
+      if (F.size() < 2) { continue; }
 
       if (!myWhitelist.empty()) {