diff --git a/ast.c b/ast.c
index daafae9..f968623 100644
--- a/ast.c
+++ b/ast.c
@@ -53,6 +53,18 @@ Node* MakeTypeNode(
     return node;
 }
 
+Node* MakeCustomTypeNode(
+    Node *identifierNode
+) {
+    Node* node = (Node*) malloc(sizeof(Node));
+    node->syntaxKind = Type;
+    node->type = CustomType;
+    node->childCount = 1;
+    node->children = (Node**) malloc(sizeof(Node*));
+    node->children[0] = identifierNode;
+    return node;
+}
+
 Node* MakeIdentifierNode(
     const char *id
 ) {
@@ -288,6 +300,7 @@ static const char* PrimitiveTypeToString(PrimitiveType type)
         case UInt: return "UInt";
         case Bool: return "Bool";
         case Void: return "Void";
+        case CustomType: return "CustomType";
     }
 
     return "Unknown";
diff --git a/ast.h b/ast.h
index a8c80bd..d96cf74 100644
--- a/ast.h
+++ b/ast.h
@@ -48,7 +48,8 @@ typedef enum
     UInt,
     Float,
     Double,
-    String
+    String,
+    CustomType
 } PrimitiveType;
 
 typedef union
@@ -81,6 +82,9 @@ const char* SyntaxKindString(SyntaxKind syntaxKind);
 Node* MakeTypeNode(
     PrimitiveType type
 );
+Node* MakeCustomTypeNode(
+    Node *identifierNode
+);
 Node* MakeIdentifierNode(
     const char *id
 );
diff --git a/compiler.c b/compiler.c
index 8738413..d68cde3 100644
--- a/compiler.c
+++ b/compiler.c
@@ -228,6 +228,38 @@ static LLVMValueRef FindVariableByName(LLVMBuilderRef builder, LLVMValueRef wStr
     return searchResult;
 }
 
+typedef struct CustomTypeMap
+{
+    LLVMTypeRef type;
+    char *name;
+} CustomTypeMap;
+
+CustomTypeMap *customTypes;
+uint32_t customTypeCount;
+
+static void RegisterCustomType(LLVMTypeRef type, char *name)
+{
+    customTypes = realloc(customTypes, sizeof(CustomType) * (customTypeCount + 1));
+    customTypes[customTypeCount].type = type;
+    customTypes[customTypeCount].name = strdup(name);
+    customTypeCount += 1;
+}
+
+static LLVMTypeRef LookupCustomType(char *name)
+{
+    uint32_t i;
+
+    for (i = 0; i < customTypeCount; i += 1)
+    {
+        if (strcmp(customTypes[i].name, name) == 0)
+        {
+            return customTypes[i].type;
+        }
+    }
+
+    return NULL;
+}
+
 static LLVMTypeRef WraithTypeToLLVMType(PrimitiveType type)
 {
     switch (type)
@@ -344,6 +376,23 @@ static void CompileAssignment(LLVMValueRef wStructValue, LLVMBuilderRef builder,
     MarkStructFieldForWrite(wStructValue, identifier);
 }
 
+static void CompileFunctionVariableDeclaration(LLVMBuilderRef builder, Node *variableDeclaration)
+{
+    char *variableName = variableDeclaration->children[1]->value.string;
+    LLVMValueRef variable;
+    if (variableDeclaration->children[0]->type == CustomType)
+    {
+        char *customTypeName = variableDeclaration->children[0]->children[0]->value.string;
+        variable = LLVMBuildAlloca(builder, LookupCustomType(customTypeName), variableName);
+    }
+    else
+    {
+        variable = LLVMBuildAlloca(builder, WraithTypeToLLVMType(variableDeclaration->children[0]->type), variableName);
+    }
+
+    AddNamedVariable(variableName, variable);
+}
+
 static uint8_t CompileStatement(LLVMValueRef wStructValue, LLVMBuilderRef builder, LLVMValueRef function, Node *statement)
 {
     switch (statement->syntaxKind)
@@ -352,6 +401,10 @@ static uint8_t CompileStatement(LLVMValueRef wStructValue, LLVMBuilderRef builde
             CompileAssignment(wStructValue, builder, function, statement);
             return 0;
 
+        case Declaration:
+            CompileFunctionVariableDeclaration(builder, statement);
+            return 0;
+
         case Return:
             CompileReturn(wStructValue, builder, function, statement);
             return 1;
@@ -470,6 +523,8 @@ static void CompileStruct(LLVMModuleRef module, LLVMContextRef context, Node *no
                 break;
         }
     }
+
+    RegisterCustomType(wStruct, node->children[0]->value.string);
 }
 
 static void Compile(LLVMModuleRef module, LLVMContextRef context, Node *node)
@@ -503,6 +558,9 @@ int main(int argc, char *argv[])
     structFieldMaps = NULL;
     structFieldMapCount = 0;
 
+    customTypes = NULL;
+    customTypeCount = 0;
+
     stack = CreateStack();
 
     FILE *fp = fopen(argv[1], "r");
diff --git a/stack.c b/stack.c
index 1fe7fe0..43c48ab 100644
--- a/stack.c
+++ b/stack.c
@@ -4,7 +4,7 @@
 
 Stack* CreateStack()
 {
-    uint32_t i;
+    int32_t i;
     Stack *stack = (Stack*) malloc(sizeof(Stack));
     stack->stackCapacity = 4;
     stack->stackFrames = (StackFrame*) malloc(sizeof(StackFrame) * stack->stackCapacity);
@@ -15,6 +15,8 @@ Stack* CreateStack()
         stack->stackFrames[i].nodeCount = 0;
     }
     stack->stackIndex = 0;
+
+    PushStackFrame(stack);
     return stack;
 }
 
@@ -26,8 +28,9 @@ void PushStackFrame(Stack *stack)
     {
         stack->stackCapacity += 1;
         stack->stackFrames = (StackFrame*) realloc(stack->stackFrames, sizeof(StackFrame) * stack->stackCapacity);
-
+        stack->stackFrames[stack->stackIndex].nodes = NULL;
         stack->stackFrames[stack->stackIndex].nodeCapacity = 0;
+        stack->stackFrames[stack->stackIndex].nodeCount = 0;
     }
 
     stack->stackFrames[stack->stackIndex].nodeCount = 0;
@@ -52,6 +55,11 @@ void AddNode(Stack *stack, Node *statementNode)
 
 Node** GetNodes(Stack *stack, uint32_t *pCount)
 {
+    if (stack->stackIndex < 0) {
+        *pCount= 0;
+        return NULL;
+    }
+
     *pCount = stack->stackFrames[stack->stackIndex].nodeCount;
     return stack->stackFrames[stack->stackIndex].nodes;
 }
diff --git a/stack.h b/stack.h
index 09c8892..549e72e 100644
--- a/stack.h
+++ b/stack.h
@@ -13,8 +13,8 @@ typedef struct StackFrame
 typedef struct Stack
 {
     StackFrame *stackFrames;
-    uint32_t stackCapacity;
-    uint32_t stackIndex;
+    int32_t stackCapacity;
+    int32_t stackIndex;
 } Stack;
 
 Stack* CreateStack();
diff --git a/wraith.y b/wraith.y
index 96a53f9..d2a0b17 100644
--- a/wraith.y
+++ b/wraith.y
@@ -158,6 +158,10 @@ VariableDeclaration     : Type Identifier
                         {
                             $$ = MakeDeclarationNode($1, $2);
                         }
+                        | Identifier Identifier
+                        {
+                            $$ = MakeDeclarationNode(MakeCustomTypeNode($1), $2);
+                        }
 
 AssignmentStatement     : VariableDeclaration EQUAL Expression
                         {