diff --git a/Chapter05/tinylang/lib/CodeGen/CGModule.cpp b/Chapter05/tinylang/lib/CodeGen/CGModule.cpp
index afd80b2..58babd2 100644
--- a/Chapter05/tinylang/lib/CodeGen/CGModule.cpp
+++ b/Chapter05/tinylang/lib/CodeGen/CGModule.cpp
@@ -47,7 +47,9 @@ void CGModule::run(ModuleDeclaration *Mod) {
       llvm::GlobalVariable *V = new llvm::GlobalVariable(
           *M, convertType(Var->getType()),
           /*isConstant=*/false,
-          llvm::GlobalValue::PrivateLinkage, nullptr,
+          llvm::GlobalValue::PrivateLinkage, 
+          llvm::ConstantAggregateZero::get(
+                  convertType(Var->getType())),
           mangleName(Var));
       Globals[Var] = V;
     } else if (auto *Proc =
diff --git a/Chapter06/tinylang/lib/CodeGen/CGModule.cpp b/Chapter06/tinylang/lib/CodeGen/CGModule.cpp
index 4ea5561..ade4e0b 100644
--- a/Chapter06/tinylang/lib/CodeGen/CGModule.cpp
+++ b/Chapter06/tinylang/lib/CodeGen/CGModule.cpp
@@ -86,7 +86,9 @@ void CGModule::run(ModuleDeclaration *Mod) {
       llvm::GlobalVariable *V = new llvm::GlobalVariable(
           *M, convertType(Var->getType()),
           /*isConstant=*/false,
-          llvm::GlobalValue::PrivateLinkage, nullptr,
+          llvm::GlobalValue::PrivateLinkage,
+          llvm::ConstantAggregateZero::get(
+                  convertType(Var->getType())),
           mangleName(Var));
       Globals[Var] = V;
     } else if (auto *Proc =
diff --git a/Chapter07/tinylang/lib/CodeGen/CGModule.cpp b/Chapter07/tinylang/lib/CodeGen/CGModule.cpp
index 9963d2c..b178c0d 100644
--- a/Chapter07/tinylang/lib/CodeGen/CGModule.cpp
+++ b/Chapter07/tinylang/lib/CodeGen/CGModule.cpp
@@ -100,7 +100,9 @@ void CGModule::run(ModuleDeclaration *Mod) {
       llvm::GlobalVariable *V = new llvm::GlobalVariable(
           *M, convertType(Var->getType()),
           /*isConstant=*/false,
-          llvm::GlobalValue::PrivateLinkage, nullptr,
+          llvm::GlobalValue::PrivateLinkage,
+          llvm::ConstantAggregateZero::get(
+                  convertType(Var->getType())),
           mangleName(Var));
       Globals[Var] = V;
       if (CGDebugInfo *Dbg = getDbgInfo())
diff --git a/Chapter08/tinylang/lib/CodeGen/CGModule.cpp b/Chapter08/tinylang/lib/CodeGen/CGModule.cpp
index 9963d2c..b178c0d 100644
--- a/Chapter08/tinylang/lib/CodeGen/CGModule.cpp
+++ b/Chapter08/tinylang/lib/CodeGen/CGModule.cpp
@@ -100,7 +100,9 @@ void CGModule::run(ModuleDeclaration *Mod) {
       llvm::GlobalVariable *V = new llvm::GlobalVariable(
           *M, convertType(Var->getType()),
           /*isConstant=*/false,
-          llvm::GlobalValue::PrivateLinkage, nullptr,
+          llvm::GlobalValue::PrivateLinkage,
+          llvm::ConstantAggregateZero::get(
+                  convertType(Var->getType())),
           mangleName(Var));
       Globals[Var] = V;
       if (CGDebugInfo *Dbg = getDbgInfo())