diff --git a/gen/dibuilder.cpp b/gen/dibuilder.cpp
index e63733a973..4cd8f16a96 100644
--- a/gen/dibuilder.cpp
+++ b/gen/dibuilder.cpp
@@ -834,8 +834,7 @@ ldc::DISubprogram ldc::DIBuilder::EmitSubProgram(FuncDeclaration *fd) {
 #endif
       );
 #if LDC_LLVM_VER >= 308
-  if (fd->fbody)
-    DtoFunction(fd)->setSubprogram(SP);
+  DtoFunction(fd)->setSubprogram(SP);
 #endif
   return SP;
 }
diff --git a/gen/functions.cpp b/gen/functions.cpp
index ff13065759..cc78249ab2 100644
--- a/gen/functions.cpp
+++ b/gen/functions.cpp
@@ -921,15 +921,24 @@ void DtoDefineFunction(FuncDeclaration *fd, bool linkageAvailableExternally) {
     return;
   }
 
-  IrFunction *irFunc = getIrFunc(fd);
+  IrFunction *const irFunc = getIrFunc(fd);
+  llvm::Function *const func = irFunc->getLLVMFunc();
 
-  // debug info
-  irFunc->diSubprogram = gIR->DBuilder.EmitSubProgram(fd);
+  if (!func->empty()) {
+    warning(fd->loc,
+            "skipping definition of function `%s` due to previous definition "
+            "for the same mangled name: %s",
+            fd->toPrettyChars(), mangleExact(fd));
+    return;
+  }
 
   if (!fd->fbody) {
     return;
   }
 
+  // debug info
+  irFunc->diSubprogram = gIR->DBuilder.EmitSubProgram(fd);
+
   IF_LOG Logger::println("Doing function body for: %s", fd->toChars());
   gIR->funcGenStates.emplace_back(new FuncGenState(*irFunc, *gIR));
   auto &funcGen = gIR->funcGen();
@@ -940,7 +949,6 @@ void DtoDefineFunction(FuncDeclaration *fd, bool linkageAvailableExternally) {
 
   const auto f = static_cast<TypeFunction *>(fd->type->toBasetype());
   IrFuncTy &irFty = irFunc->irFty;
-  llvm::Function *func = irFunc->getLLVMFunc();
 
   const auto lwc = lowerFuncLinkage(fd);
   if (linkageAvailableExternally) {