diff --git a/armsrc/appmain.c b/armsrc/appmain.c
index b8823af3b..dded4be55 100644
--- a/armsrc/appmain.c
+++ b/armsrc/appmain.c
@@ -851,11 +851,7 @@ static void PacketReceived(PacketCommandNG *packet) {
             break;
         }
         case CMD_LF_ACQ_RAW_ADC: {
-            struct p {
-                uint32_t samples : 31;
-                bool     verbose : 1;
-            } PACKED;
-            struct p *payload = (struct p *)packet->data.asBytes;
+            lf_sample_payload_t *payload = (lf_sample_payload_t *)packet->data.asBytes;
             uint32_t bits = SampleLF(payload->verbose, payload->samples, true);
             reply_ng(CMD_LF_ACQ_RAW_ADC, PM3_SUCCESS, (uint8_t *)&bits, sizeof(bits));
             break;
@@ -880,11 +876,7 @@ static void PacketReceived(PacketCommandNG *packet) {
             break;
         }
         case CMD_LF_SNIFF_RAW_ADC: {
-            struct p {
-                uint32_t samples : 31;
-                bool     verbose : 1;
-            } PACKED;
-            struct p *payload = (struct p *)packet->data.asBytes;
+            lf_sample_payload_t *payload = (lf_sample_payload_t *)packet->data.asBytes;
 
             uint32_t bits = SniffLF(payload->verbose, payload->samples, true);
             reply_ng(CMD_LF_SNIFF_RAW_ADC, PM3_SUCCESS, (uint8_t *)&bits, sizeof(bits));
diff --git a/client/src/cmdlf.c b/client/src/cmdlf.c
index 1d57378c7..ce0e67ff5 100644
--- a/client/src/cmdlf.c
+++ b/client/src/cmdlf.c
@@ -699,12 +699,7 @@ int CmdLFConfig(const char *Cmd) {
 int lf_read(bool verbose, uint32_t samples) {
     if (!g_session.pm3_present) return PM3_ENOTTY;
 
-    struct p {
-        uint32_t samples : 31;
-        bool     verbose : 1;
-    } PACKED;
-
-    struct p payload;
+    lf_sample_payload_t payload;
     payload.verbose = verbose;
     payload.samples = samples;
 
@@ -765,10 +760,7 @@ int CmdLFRead(const char *Cmd) {
 int lf_sniff(bool verbose, uint32_t samples) {
     if (!g_session.pm3_present) return PM3_ENOTTY;
 
-    struct p {
-        uint32_t samples : 31;
-        bool     verbose : 1;
-    } PACKED payload;
+    lf_sample_payload_t payload;
 
     payload.samples = (samples & 0xFFFF);
     payload.verbose = verbose;
diff --git a/include/pm3_cmd.h b/include/pm3_cmd.h
index af019eadd..4b0b21c0e 100644
--- a/include/pm3_cmd.h
+++ b/include/pm3_cmd.h
@@ -274,6 +274,17 @@ typedef struct {
     uint8_t data[];
 } PACKED lf_hitag_t;
 
+// For CMD_LF_SNIFF_RAW_ADC and CMD_LF_ACQ_RAW_ADC
+#define LF_SAMPLES_BITS 30
+#define MAX_LF_SAMPLES ((((uint32_t)1u) << LF_SAMPLES_BITS) - 1)
+
+typedef struct {
+    // 64KB SRAM -> 524288 bits(max sample num) < 2^30
+    uint32_t samples  : LF_SAMPLES_BITS;
+    bool     realtime : 1;
+    bool     verbose  : 1;
+} PACKED lf_sample_payload_t;
+
 typedef struct {
     uint8_t blockno;
     uint8_t keytype;