diff --git a/config/src/config.rs b/config/src/config.rs
index 25f93e8..0fce309 100644
--- a/config/src/config.rs
+++ b/config/src/config.rs
@@ -131,6 +131,7 @@ pub struct FuzzerConfig {
     pub dump_python_code_for_inputs: Option<bool>,
     pub exit_after_first_crash: bool,
     pub write_protected_input_buffer: bool,
+    pub cow_primary_size: Option<u64>,
 }
 impl FuzzerConfig{
     pub fn new_from_loader(sharedir: &str, default: FuzzerConfigLoader, config: FuzzerConfigLoader) -> Self {
@@ -159,6 +160,7 @@ impl FuzzerConfig{
             dump_python_code_for_inputs: config.dump_python_code_for_inputs.or(default.dump_python_code_for_inputs),
             exit_after_first_crash: config.exit_after_first_crash.unwrap_or(default.exit_after_first_crash.unwrap_or(false)),
             write_protected_input_buffer: config.write_protected_input_buffer,
+            cow_primary_size: if config.cow_primary_size != 0 { Some( config.cow_primary_size as u64) } else { None },
         }
     }
 }
diff --git a/config/src/loader.rs b/config/src/loader.rs
index 4cd6be9..6a25f59 100644
--- a/config/src/loader.rs
+++ b/config/src/loader.rs
@@ -39,6 +39,9 @@ pub struct FuzzerConfigLoader {
     #[serde(default = "default_write_protected_input_buffer")]
     pub write_protected_input_buffer: bool,
 
+    #[serde(default = "default_cow_primary_size")]
+    pub cow_primary_size: u64,
+
     pub workdir_path: Option<String>,
     pub bitmap_size: Option<usize>,
     pub mem_limit: Option<usize>,
@@ -58,6 +61,10 @@ fn default_write_protected_input_buffer() -> bool {
     false
 }
 
+fn default_cow_primary_size() -> u64 {
+    0
+}
+
 #[derive(Clone, Serialize, Deserialize)]
 pub struct ConfigLoader {
     pub include_default_config_path: Option<String>,
diff --git a/fuzz_runner/src/nyx/mod.rs b/fuzz_runner/src/nyx/mod.rs
index fccadd2..1556207 100644
--- a/fuzz_runner/src/nyx/mod.rs
+++ b/fuzz_runner/src/nyx/mod.rs
@@ -38,6 +38,7 @@ pub fn qemu_process_new_from_kernel(sharedir: String, cfg: &QemuKernelConfig, fu
             Some(x) => x,
         },
         write_protected_input_buffer: fuzz_cfg.write_protected_input_buffer,
+        cow_primary_size: fuzz_cfg.cow_primary_size, 
     };
     let qemu_id =  fuzz_cfg.thread_id;
     let qemu_params = params::QemuParams::new_from_kernel(&fuzz_cfg.workdir_path, qemu_id, &params, fuzz_cfg.threads > 1);
@@ -78,6 +79,7 @@ pub fn qemu_process_new_from_snapshot(sharedir: String, cfg: &QemuSnapshotConfig
             Some(x) => x,
         },
         write_protected_input_buffer: fuzz_cfg.write_protected_input_buffer,
+        cow_primary_size: fuzz_cfg.cow_primary_size, 
     };
     let qemu_id = fuzz_cfg.thread_id;
     let qemu_params = params::QemuParams::new_from_snapshot(&fuzz_cfg.workdir_path, qemu_id, fuzz_cfg.cpu_pin_start_at, &params, fuzz_cfg.threads > 1);
diff --git a/fuzz_runner/src/nyx/params.rs b/fuzz_runner/src/nyx/params.rs
index 88e69dd..9f423c9 100644
--- a/fuzz_runner/src/nyx/params.rs
+++ b/fuzz_runner/src/nyx/params.rs
@@ -12,6 +12,7 @@ pub struct KernelVmParams {
 
     pub dump_python_code_for_inputs: bool,
     pub write_protected_input_buffer: bool,
+    pub cow_primary_size: Option<u64>,
 }
 
 pub struct SnapshotVmParams{
@@ -26,6 +27,7 @@ pub struct SnapshotVmParams{
 
     pub dump_python_code_for_inputs: bool,
     pub write_protected_input_buffer: bool,
+    pub cow_primary_size: Option<u64>,
 }
 
 pub struct QemuParams {
@@ -42,6 +44,7 @@ pub struct QemuParams {
 
     pub dump_python_code_for_inputs: bool,
     pub write_protected_input_buffer: bool,
+    pub cow_primary_size: Option<u64>,
 }
 
 impl QemuParams {
@@ -108,6 +111,11 @@ impl QemuParams {
         nyx_ops += &format!(",worker_id={}", qemu_id);
         nyx_ops += &format!(",workdir={}", workdir);
         nyx_ops += &format!(",sharedir={}", params.sharedir);
+
+        if params.cow_primary_size.is_some(){
+            nyx_ops += &format!(",cow_primary_size={}", params.cow_primary_size.unwrap());
+        }
+
         //nyx_ops += &format!(",ip0_a=0x1000,ip0_b=0x7ffffffff000");
         //nyx_ops += &format!(",ip0_a=ffff800000000000,ip0_b=ffffffffffffffff");
 
@@ -156,6 +164,7 @@ impl QemuParams {
             payload_size: (1 << 16),
             dump_python_code_for_inputs: params.dump_python_code_for_inputs,
             write_protected_input_buffer: params.write_protected_input_buffer,
+            cow_primary_size: params.cow_primary_size,
         };
     }
 
@@ -227,6 +236,10 @@ impl QemuParams {
         nyx_ops += &format!(",workdir={}", workdir);
         nyx_ops += &format!(",sharedir={}", params.sharedir);
 
+        if params.cow_primary_size.is_some(){
+            nyx_ops += &format!(",cow_primary_size={}", params.cow_primary_size.unwrap());
+        }
+
         //nyx_ops += &format!(",ip0_a=0x1000,ip0_b=0x7ffffffff000");
         //nyx_ops += &format!(",ip0_a=ffff800000000000,ip0_b=ffffffffffffffff");
 
@@ -266,6 +279,7 @@ impl QemuParams {
             payload_size: (128 << 10),
             dump_python_code_for_inputs: params.dump_python_code_for_inputs,
             write_protected_input_buffer: params.write_protected_input_buffer,
+            cow_primary_size: params.cow_primary_size,
         };
     }
 }