diff --git a/enzyme/Enzyme/Clang/EnzymeClang.cpp b/enzyme/Enzyme/Clang/EnzymeClang.cpp
index 8891d1b75772..77fecd109c82 100644
--- a/enzyme/Enzyme/Clang/EnzymeClang.cpp
+++ b/enzyme/Enzyme/Clang/EnzymeClang.cpp
@@ -81,7 +81,7 @@ struct Visitor : public RecursiveASTVisitor<Visitor> {
 };
 
 #if LLVM_VERSION_MAJOR >= 18
-void registerEnzyme(llvm::PassBuilder &PB);
+extern "C" void registerEnzyme(llvm::PassBuilder &PB);
 #endif
 
 class EnzymePlugin final : public clang::ASTConsumer {
diff --git a/enzyme/Enzyme/Enzyme.cpp b/enzyme/Enzyme/Enzyme.cpp
index 9185649faac5..013d6812fcae 100644
--- a/enzyme/Enzyme/Enzyme.cpp
+++ b/enzyme/Enzyme/Enzyme.cpp
@@ -3658,7 +3658,7 @@ void augmentPassBuilder(llvm::PassBuilder &PB) {
   PB.registerFullLinkTimeOptimizationEarlyEPCallback(loadLTO);
 }
 
-void registerEnzyme(llvm::PassBuilder &PB) {
+extern "C" void registerEnzyme(llvm::PassBuilder &PB) {
 #ifdef ENZYME_RUNPASS
   augmentPassBuilder(PB);
 #endif
diff --git a/enzyme/Enzyme/eopt.cpp b/enzyme/Enzyme/eopt.cpp
index ab8792d34996..3d040e0ce617 100644
--- a/enzyme/Enzyme/eopt.cpp
+++ b/enzyme/Enzyme/eopt.cpp
@@ -5,7 +5,7 @@
 
 using namespace llvm;
 
-void registerEnzyme(llvm::PassBuilder &PB);
+extern "C" void registerEnzyme(llvm::PassBuilder &PB);
 
 extern "C" int optMain(int argc, char **argv,
                        llvm::ArrayRef<std::function<void(llvm::PassBuilder &)>>