diff --git a/docs/Module Developer's Guide.md b/docs/Module Developer's Guide.md
index 663df2b2e..881f70d9b 100644
--- a/docs/Module Developer's Guide.md	
+++ b/docs/Module Developer's Guide.md	
@@ -12,7 +12,6 @@ For illustrative purposes we are going to create a `text` module that allows
 creating YARA rules for plain-text files, based on the number of lines and
 words
 
-- [Module Developer's Guide](#module-developers-guide)
   - [Defining the module's structure](#defining-the-modules-structure)
   - [Proto2 vs Proto3](#proto2-vs-proto3)
   - [Tweaking the module's YAML output](#tweaking-the-modules-yaml-output)
@@ -65,6 +64,7 @@ option (yara.module_options) = {
   name : "text"
   root_message: "text.Text"
   rust_module: "text"
+  cargo_feature: "text-module"
 };
 
 message Text {
@@ -121,6 +121,7 @@ option (yara.module_options) = {
   name : "text"
   root_message: "text.Text"
   rust_module: "text"
+  cargo_feature: "text-module"
 };
 ```
 
@@ -131,16 +132,24 @@ file, but one describing a module. In fact, you can put any `.proto` file in the
 files is describing a YARA module. Only files containing a `yara.module_options` 
 section will define a module.
 
-Options `name` and `root_message` are required, while `rust_module` is optional.
-The `name` option defines the module's name. This is the name that will be used
-for importing the module in a YARA rule, in this case our module will be imported
-with `import "text"`. The `root_message` option indicates which is the module's 
-root structure, it must contain the name of some structure (a.k.a message) defined 
-in the `.proto` file. In our case the value for `root_message` is `"text.Text"` 
-because we have defined our module's structure in a message named `Text`, which
-is under package `text`. In general the value in this field will have the form
-`package.Message`, except if the `package` statement is missing, in which case
-it would be the name of the message alone (i.e: `Text`).
+Options `name` and `root_message` are required, while `rust_module` and 
+`cargo_feature` are optional. The `name` option defines the module's name. This 
+is the name that will be used for importing the module in a YARA rule, in this 
+case our module will be imported with `import "text"`.
+
+The `cargo_feature` option indicates the name of the feature that controls whether
+the module is built or not. If this option is not specified the module is always
+built, but if you specify a feature name, this feature name must also be included
+in the `Cargo.toml` file, and the module will be built only when this `cargo`
+feature is enabled.
+
+The `root_message` option a very important option indicating which is the module's
+root structure, it must contain the name of some structure (a.k.a. message) 
+defined in the `.proto` file. In our case the value for `root_message` is 
+`"text.Text"` because we have defined our module's structure in a message named 
+`Text`, which is under package `text`. In general the value in this field will 
+have the form `package.Message`, except if the `package` statement is missing, 
+in which case it would be the name of the message alone (i.e: `Text`).
 
 The `root_message` field is required because your `.proto` file can define
 multiple messages, and YARA needs to know which of them is considered the root 
diff --git a/lib/build.rs b/lib/build.rs
index cabd1f909..32e4c3857 100644
--- a/lib/build.rs
+++ b/lib/build.rs
@@ -121,7 +121,7 @@ fn main() {
             yara_module_options.get(&proto_file.options)
         {
             modules.push((
-                module_options.name,
+                module_options.name.unwrap(),
                 proto_file
                     .name
                     .unwrap()
@@ -129,7 +129,8 @@ fn main() {
                     .unwrap()
                     .to_string(),
                 module_options.rust_module,
-                module_options.root_message,
+                module_options.cargo_feature,
+                module_options.root_message.unwrap(),
             ));
         }
     }
@@ -164,37 +165,44 @@ fn main() {
         let name = m.0;
         let proto_mod = m.1;
         let rust_mod = m.2;
-        let root_message = m.3;
-
-        if !rust_mod.is_empty() {
-            write!(
-                modules_rs,
-                r#"
-#[cfg(feature = "{name}-module")]
-mod {rust_mod};"#,
-            )
-            .unwrap();
-        }
+        let cargo_feature = m.3;
+        let root_message = m.4;
 
         // If the YARA module has an associated Rust module, this module must
         // have a function named "main". If the YARA module doesn't have an
         // associated YARA module, the main function is set to None.
-        let main_fn = if !rust_mod.is_empty() {
+        let main_fn = if let Some(rust_mod) = &rust_mod {
             format!("Some({}::__main__ as MainFn)", rust_mod)
         } else {
             "None".to_string()
         };
 
-        let rust_mod_name = if !rust_mod.is_empty() {
+        let rust_mod_name = if let Some(rust_mod) = &rust_mod {
             format!(r#"Some("{}")"#, rust_mod)
         } else {
             "None".to_string()
         };
 
+        let cfg_feature = if let Some(cargo_feature) = &cargo_feature {
+            format!(r#"#[cfg(feature = "{cargo_feature}")]"#)
+        } else {
+            "".to_string()
+        };
+
+        if let Some(rust_mod) = &rust_mod {
+            write!(
+                modules_rs,
+                r#"
+{cfg_feature}
+mod {rust_mod};"#,
+            )
+            .unwrap();
+        }
+
         write!(
             add_modules_rs,
             r#"
-#[cfg(feature = "{name}-module")]
+{cfg_feature}
 add_module!(modules, "{name}", {proto_mod}, "{root_message}", {rust_mod_name}, {main_fn});"#,
         )
         .unwrap();
diff --git a/lib/src/modules/protos/console.proto b/lib/src/modules/protos/console.proto
index 05ce59fc7..40d615584 100644
--- a/lib/src/modules/protos/console.proto
+++ b/lib/src/modules/protos/console.proto
@@ -7,6 +7,7 @@ option (yara.module_options) = {
   name : "console"
   root_message: "console.Console"
   rust_module: "console"
+  cargo_feature: "console-module"
 };
 
 message Console {
diff --git a/lib/src/modules/protos/dotnet.proto b/lib/src/modules/protos/dotnet.proto
index bb5239e2d..6eb817ce2 100644
--- a/lib/src/modules/protos/dotnet.proto
+++ b/lib/src/modules/protos/dotnet.proto
@@ -7,6 +7,7 @@ option (yara.module_options) = {
   name : "dotnet"
   root_message: "dotnet.Dotnet"
   rust_module: "dotnet"
+  cargo_feature: "dotnet-module"
 };
 
 message Dotnet {
diff --git a/lib/src/modules/protos/elf.proto b/lib/src/modules/protos/elf.proto
index b99e5bb27..006f88cb2 100644
--- a/lib/src/modules/protos/elf.proto
+++ b/lib/src/modules/protos/elf.proto
@@ -7,6 +7,7 @@ option (yara.module_options) = {
   name : "elf"
   root_message: "elf.ELF"
   rust_module: "elf"
+  cargo_feature: "elf-module"
 };
 
 message ELF {
diff --git a/lib/src/modules/protos/hash.proto b/lib/src/modules/protos/hash.proto
index 488f2a871..888b435a7 100644
--- a/lib/src/modules/protos/hash.proto
+++ b/lib/src/modules/protos/hash.proto
@@ -7,6 +7,7 @@ option (yara.module_options) = {
   name : "hash"
   root_message: "hash.Hash"
   rust_module: "hash"
+  cargo_feature: "hash-module"
 };
 
 message Hash {
diff --git a/lib/src/modules/protos/lnk.proto b/lib/src/modules/protos/lnk.proto
index 049d2f149..df4305bff 100644
--- a/lib/src/modules/protos/lnk.proto
+++ b/lib/src/modules/protos/lnk.proto
@@ -7,6 +7,7 @@ option (yara.module_options) = {
   name : "lnk"
   root_message: "lnk.Lnk"
   rust_module: "lnk"
+  cargo_feature: "lnk-module"
 };
 
 enum FileAttributes {
diff --git a/lib/src/modules/protos/macho.proto b/lib/src/modules/protos/macho.proto
index 8dfd00475..886784349 100644
--- a/lib/src/modules/protos/macho.proto
+++ b/lib/src/modules/protos/macho.proto
@@ -8,6 +8,7 @@ option (yara.module_options) = {
   name : "macho"
   root_message: "macho.Macho"
   rust_module: "macho"
+  cargo_feature: "macho-module"
 };
 
 message Dylib {
diff --git a/lib/src/modules/protos/math.proto b/lib/src/modules/protos/math.proto
index edd5ed3bb..7a74645da 100644
--- a/lib/src/modules/protos/math.proto
+++ b/lib/src/modules/protos/math.proto
@@ -7,6 +7,7 @@ option (yara.module_options) = {
   name : "math"
   root_message: "math.Math"
   rust_module: "math"
+  cargo_feature: "math-module"
 };
 
 message Math {
diff --git a/lib/src/modules/protos/pe.proto b/lib/src/modules/protos/pe.proto
index 37204d27b..2da3b5e58 100644
--- a/lib/src/modules/protos/pe.proto
+++ b/lib/src/modules/protos/pe.proto
@@ -9,6 +9,7 @@ option (yara.module_options) = {
   name : "pe"
   root_message: "pe.PE"
   rust_module: "pe"
+  cargo_feature: "pe-module"
 };
 
 message PE {
diff --git a/lib/src/modules/protos/string.proto b/lib/src/modules/protos/string.proto
index 4d5a34b3a..286b44410 100644
--- a/lib/src/modules/protos/string.proto
+++ b/lib/src/modules/protos/string.proto
@@ -7,6 +7,7 @@ option (yara.module_options) = {
   name : "string"
   root_message: "string.String"
   rust_module: "string"
+  cargo_feature: "string-module"
 };
 
 message String {
diff --git a/lib/src/modules/protos/test_proto2.proto b/lib/src/modules/protos/test_proto2.proto
index 668970bd2..434daaf98 100644
--- a/lib/src/modules/protos/test_proto2.proto
+++ b/lib/src/modules/protos/test_proto2.proto
@@ -45,6 +45,10 @@ option (yara.module_options) = {
   // in the data structure defined by this proto file, and don't need to have
   // any associated code.
   rust_module: "test_proto2"
+  
+  // The name of the feature that controls whether this module is compiled or
+  // not. A feature with this name must be added to the Cargo.toml file.
+  cargo_feature: "test_proto2-module"
 };
 
 /// Top-level structure for this module.
diff --git a/lib/src/modules/protos/test_proto3.proto b/lib/src/modules/protos/test_proto3.proto
index d6235e3d5..1163073c6 100644
--- a/lib/src/modules/protos/test_proto3.proto
+++ b/lib/src/modules/protos/test_proto3.proto
@@ -45,6 +45,10 @@ option (yara.module_options) = {
   // in the data structure defined by this proto file, and don't need to have
   // any associated code.
   rust_module: "test_proto3"
+
+  // The name of the feature that controls whether this module is compiled or
+  // not. A feature with this name must be added to the Cargo.toml file.
+  cargo_feature: "test_proto3-module"
 };
 
 /// Top-level structure for this module.
diff --git a/lib/src/modules/protos/text.proto b/lib/src/modules/protos/text.proto
index e66eaf29e..b0e38fc48 100644
--- a/lib/src/modules/protos/text.proto
+++ b/lib/src/modules/protos/text.proto
@@ -15,6 +15,9 @@ option (yara.module_options) = {
   // The Rust module implementing this YARA module is named `text`. It can
   // be found in `src/modules/text.rs`.
   rust_module: "text"
+  // The feature that controls whether this module is compiled or not is named
+  // `text-module`.
+  cargo_feature: "text-module"
 };
 
 // This is the module's root structure.
diff --git a/lib/src/modules/protos/time.proto b/lib/src/modules/protos/time.proto
index 0056c55fe..79351d4cd 100644
--- a/lib/src/modules/protos/time.proto
+++ b/lib/src/modules/protos/time.proto
@@ -7,6 +7,7 @@ option (yara.module_options) = {
   name : "time"
   root_message: "time.Time"
   rust_module: "time"
+  cargo_feature: "time-module"
 };
 
 message Time {
diff --git a/lib/src/types/structure.rs b/lib/src/types/structure.rs
index f9fecd54c..e16e123e1 100644
--- a/lib/src/types/structure.rs
+++ b/lib/src/types/structure.rs
@@ -412,7 +412,7 @@ impl Struct {
         if let Some(options) =
             module_options.get(&file_descriptor.proto().options)
         {
-            options.root_message == msg_descriptor.full_name()
+            options.root_message.unwrap() == msg_descriptor.full_name()
         } else {
             false
         }
@@ -438,11 +438,7 @@ impl Struct {
         if let Some(options) =
             enum_options.get(&enum_descriptor.proto().options)
         {
-            if options.name.is_empty() {
-                enum_descriptor.name().to_owned()
-            } else {
-                options.name.clone()
-            }
+            options.name.unwrap_or_else(|| enum_descriptor.name().to_owned())
         } else {
             enum_descriptor.name().to_owned()
         }
@@ -484,7 +480,7 @@ impl Struct {
         if let Some(options) =
             enum_options.get(&enum_descriptor.proto().options)
         {
-            options.inline
+            options.inline.unwrap_or(false)
         } else {
             false
         }
@@ -529,7 +525,7 @@ impl Struct {
         if let Some(options) =
             enum_value.get(&enum_value_descriptor.proto().options)
         {
-            options.i64
+            options.i64.unwrap_or_else(|| enum_value_descriptor.value() as i64)
         } else {
             enum_value_descriptor.value() as i64
         }
@@ -552,11 +548,7 @@ impl Struct {
         if let Some(options) =
             field_options.get(&field_descriptor.proto().options)
         {
-            if options.name.is_empty() {
-                field_descriptor.name().to_owned()
-            } else {
-                options.name.clone()
-            }
+            options.name.unwrap_or_else(|| field_descriptor.name().to_owned())
         } else {
             field_descriptor.name().to_owned()
         }
@@ -575,7 +567,7 @@ impl Struct {
         if let Some(options) =
             field_options.get(&field_descriptor.proto().options)
         {
-            options.ignore
+            options.ignore.unwrap_or(false)
         } else {
             false
         }
diff --git a/mod.cfg b/mod.cfg
new file mode 100644
index 000000000..1f1e27969
--- /dev/null
+++ b/mod.cfg
@@ -0,0 +1,20 @@
+{
+  "includes": [
+    "../../atlas/vt-protos/protos/tools",
+    "../../atlas/vt-protos/protos"
+  ],
+  "inputs": [
+    "../../atlas/vt-protos/protos/titan.proto",
+    "../../atlas/vt-protos/protos/filetypes.proto",
+    "../../atlas/vt-protos/protos/sandbox.proto",
+    "../../atlas/vt-protos/protos/vtnet.proto",
+    "../../atlas/vt-protos/protos/submitter.proto",
+    "../../atlas/vt-protos/protos/analysis.proto",
+    "../../atlas/vt-protos/protos/tools/net_analysis.proto",
+    "../../atlas/vt-protos/protos/tools/snort.proto",
+    "../../atlas/vt-protos/protos/tools/suricata.proto",
+    "../../atlas/vt-protos/protos/tools/tshark.proto",
+    "../../atlas/vt-protos/protos/sigma.proto",
+    "../../atlas/vt-protos/protos/relationships.proto"
+  ]
+}
\ No newline at end of file
diff --git a/proto/src/yara.proto b/proto/src/yara.proto
index 669a2e300..dbf731326 100644
--- a/proto/src/yara.proto
+++ b/proto/src/yara.proto
@@ -1,52 +1,53 @@
 // Protocol buffer that specifies the options that can be used in other protos
 // for controlling the generation of YARA modules.
 
-syntax = "proto3";
+syntax = "proto2";
 
 package yara;
 
 import "google/protobuf/descriptor.proto";
 
 message ModuleOptions {
-  string name = 1;
-  string root_message = 2;
-  string rust_module = 3;
+  required string name = 1;
+  required string root_message = 2;
+  optional string rust_module = 3;
+  optional string cargo_feature = 4;
 }
 
 message FieldOptions {
-  string name = 1;
-  bool ignore = 2;
+  optional string name = 1;
+  optional bool ignore = 2;
 }
 
 message MessageOptions {
-  string name = 1;
+  optional string name = 1;
 }
 
 message EnumOptions {
-  string name = 1;
-  bool inline = 2;
+  optional string name = 1;
+  optional bool inline = 2;
 }
 
 message EnumValueOptions {
-  int64 i64 = 1;
+  optional int64 i64 = 1;
 }
 
 extend google.protobuf.FileOptions {
-  ModuleOptions module_options = 51503;
+  optional ModuleOptions module_options = 51503;
 }
 
 extend google.protobuf.FieldOptions {
-  FieldOptions field_options = 51504;
+  optional FieldOptions field_options = 51504;
 }
 
 extend google.protobuf.MessageOptions {
-  MessageOptions message_options = 51505;
+  optional MessageOptions message_options = 51505;
 }
 
 extend google.protobuf.EnumOptions {
-  EnumOptions enum_options = 51506;
+  optional EnumOptions enum_options = 51506;
 }
 
 extend google.protobuf.EnumValueOptions {
-  EnumValueOptions enum_value = 51507;
+  optional EnumValueOptions enum_value = 51507;
 }
\ No newline at end of file