diff --git a/CMakeLists.txt b/CMakeLists.txt
index a3cbf9e..9898440 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -43,10 +43,12 @@ add_executable(
 	src/codegen.h
 	src/identcheck.h
 	src/parser.h
+	src/util.h
     src/ast.c
 	src/codegen.c
 	src/identcheck.c
 	src/parser.c
+	src/util.c
 	src/main.c
 	# Generated code
     ${BISON_Parser_OUTPUTS}
diff --git a/src/codegen.c b/src/codegen.c
index bcc3eb4..f94e192 100644
--- a/src/codegen.c
+++ b/src/codegen.c
@@ -14,6 +14,7 @@
 #include <llvm-c/Transforms/Utils.h>
 
 #include "ast.h"
+#include "util.h"
 
 typedef struct LocalVariable
 {
@@ -56,15 +57,11 @@ typedef struct StructTypeFunction
     uint8_t isStatic;
 } StructTypeFunction;
 
-typedef struct StructTypeGenericFunction
-{
-    char *name;
-    Node *functionDeclarationNode;
-} StructTypeGenericFunction;
-
 typedef struct MonomorphizedGenericFunctionHashEntry
 {
     uint64_t key;
+    TypeTag **types;
+    uint32_t typeCount;
     StructTypeFunction function;
 } MonomorphizedGenericFunctionHashEntry;
 
@@ -74,6 +71,17 @@ typedef struct MonomorphizedGenericFunctionHashArray
     uint32_t count;
 } MonomorphizedGenericFunctionHashArray;
 
+#define NUM_MONOMORPHIZED_HASH_BUCKETS 1031
+
+typedef struct StructTypeGenericFunction
+{
+    char *name;
+    Node *functionDeclarationNode;
+    uint8_t isStatic;
+    MonomorphizedGenericFunctionHashArray
+        monomorphizedFunctions[NUM_MONOMORPHIZED_HASH_BUCKETS];
+} StructTypeGenericFunction;
+
 typedef struct StructTypeDeclaration
 {
     char *name;
@@ -87,8 +95,6 @@ typedef struct StructTypeDeclaration
 
     StructTypeGenericFunction *genericFunctions;
     uint32_t genericFunctionCount;
-
-    MonomorphizedGenericFunctionHashArray monomorphizedGenericFunctions;
 } StructTypeDeclaration;
 
 StructTypeDeclaration *structTypeDeclarations;
@@ -296,8 +302,6 @@ static void AddStructDeclaration(
     structTypeDeclarations[index].functionCount = 0;
     structTypeDeclarations[index].genericFunctions = NULL;
     structTypeDeclarations[index].genericFunctionCount = 0;
-    structTypeDeclarations[index].monomorphizedGenericFunctions.elements = NULL;
-    structTypeDeclarations[index].monomorphizedGenericFunctions.count = 0;
 
     for (i = 0; i < fieldDeclarationCount; i += 1)
     {
@@ -350,9 +354,10 @@ static void DeclareStructFunction(
 static void DeclareGenericStructFunction(
     LLVMTypeRef wStructPointerType,
     Node *functionDeclarationNode,
+    uint8_t isStatic,
     char *name)
 {
-    uint32_t i, index;
+    uint32_t i, j, index;
 
     for (i = 0; i < structTypeDeclarationCount; i += 1)
     {
@@ -364,6 +369,21 @@ static void DeclareGenericStructFunction(
             structTypeDeclarations[i]
                 .genericFunctions[index]
                 .functionDeclarationNode = functionDeclarationNode;
+            structTypeDeclarations[i].genericFunctions[index].isStatic =
+                isStatic;
+
+            for (j = 0; j < NUM_MONOMORPHIZED_HASH_BUCKETS; j += 1)
+            {
+                structTypeDeclarations[i]
+                    .genericFunctions[index]
+                    .monomorphizedFunctions[j]
+                    .elements = NULL;
+                structTypeDeclarations[i]
+                    .genericFunctions[index]
+                    .monomorphizedFunctions[j]
+                    .count = 0;
+            }
+
             structTypeDeclarations[i].genericFunctionCount += 1;
 
             return;
@@ -411,6 +431,20 @@ static LLVMTypeRef ResolveType(Node *typeNode)
     }
 }
 
+static inline uint64_t HashTypeTags(TypeTag **tags, uint32_t count)
+{
+    const uint64_t HASH_FACTOR = 97;
+    uint64_t result = 1;
+    uint32_t i;
+
+    for (i = 0; i < count; i += 1)
+    {
+        result *= HASH_FACTOR + str_hash(TypeTagToString(tags[i]));
+    }
+
+    return result;
+}
+
 static LLVMValueRef LookupGenericFunction(
     StructTypeGenericFunction *genericFunction,
     TypeTag **genericArgumentTypes,
@@ -418,8 +452,46 @@ static LLVMValueRef LookupGenericFunction(
     LLVMTypeRef *pReturnType,
     uint8_t *pStatic)
 {
-    /* TODO: hash the argument types */
-    /* TODO: compile the monomorphism if doesnt exist */
+    uint32_t i, j;
+    uint64_t typeHash =
+        HashTypeTags(genericArgumentTypes, genericArgumentTypeCount);
+    uint8_t match = 0;
+
+    MonomorphizedGenericFunctionHashArray *hashArray =
+        &genericFunction->monomorphizedFunctions
+             [typeHash % NUM_MONOMORPHIZED_HASH_BUCKETS];
+
+    MonomorphizedGenericFunctionHashEntry *hashEntry = NULL;
+    for (i = 0; i < hashArray->count; i += 1)
+    {
+        match = 1;
+
+        for (j = 0; j < hashArray->elements[i].typeCount; j += 1)
+        {
+            if (hashArray->elements[i].types[j] != genericArgumentTypes[j])
+            {
+                match = 0;
+                break;
+            }
+        }
+
+        if (match)
+        {
+            hashEntry = &hashArray->elements[i];
+            break;
+        }
+    }
+
+    if (hashEntry == NULL)
+    {
+
+        /* TODO: compile */
+    }
+
+    *pReturnType = hashEntry->function.returnType;
+    *pStatic = hashEntry->function.isStatic;
+
+    return hashEntry->function.function;
 }
 
 static LLVMValueRef LookupFunctionByType(
@@ -1257,6 +1329,7 @@ static void CompileFunction(
         DeclareGenericStructFunction(
             wStructPointerType,
             functionDeclaration,
+            isStatic,
             functionName);
     }
 
diff --git a/src/util.c b/src/util.c
index 8001d03..aa5b4fb 100644
--- a/src/util.c
+++ b/src/util.c
@@ -1,7 +1,6 @@
 #include "util.h"
 
 #include <stdlib.h>
-#include <string.h>
 
 char *strdup(const char *s)
 {
@@ -15,3 +14,16 @@ char *strdup(const char *s)
     memcpy(result, s, slen + 1);
     return result;
 }
+
+uint64_t str_hash(char *str)
+{
+    uint64_t hash = 5381;
+    size_t c;
+
+    while (c = *str++)
+    {
+        hash = ((hash << 5) + hash) + c; /* hash * 33 + c */
+    }
+
+    return hash;
+}
diff --git a/src/util.h b/src/util.h
index 884fa24..108211b 100644
--- a/src/util.h
+++ b/src/util.h
@@ -1,8 +1,10 @@
 #ifndef WRAITH_UTIL_H
 #define WRAITH_UTIL_H
 
+#include <stdint.h>
 #include <string.h>
 
 char *strdup(const char *s);
+uint64_t str_hash(char *str);
 
 #endif /* WRAITH_UTIL_H */