diff --git a/devices/video/atimach64gx.cpp b/devices/video/atimach64gx.cpp
index 647d63f..5979103 100644
--- a/devices/video/atimach64gx.cpp
+++ b/devices/video/atimach64gx.cpp
@@ -797,6 +797,7 @@ void AtiMach64Gx::rgb514_write_reg(uint8_t reg_addr, uint8_t value)
     switch (reg_addr) {
     case Rgb514::CLUT_ADDR_WR:
         this->clut_index = value;
+        this->comp_index = 0;
         break;
     case Rgb514::CLUT_DATA:
         this->clut_color[this->comp_index++] = value;
diff --git a/devices/video/atimach64gx.h b/devices/video/atimach64gx.h
index e48bf82..8c5edc3 100644
--- a/devices/video/atimach64gx.h
+++ b/devices/video/atimach64gx.h
@@ -87,12 +87,12 @@ private:
     uint32_t    mm_regs_offset = 0;
 
     // RGB514 RAMDAC state
-    uint8_t     dac_idx_lo;
-    uint8_t     dac_idx_hi;
-    uint8_t     clut_index;
-    uint8_t     comp_index;
-    uint8_t     clut_color[3];
-    uint8_t     dac_regs[256];
+    uint8_t     dac_idx_lo = 0;
+    uint8_t     dac_idx_hi = 0;
+    uint8_t     clut_index = 0;
+    uint8_t     comp_index = 0;
+    uint8_t     clut_color[3] = {0};
+    uint8_t     dac_regs[256] = {0};
 
     std::unique_ptr<DisplayID>  disp_id;
     std::unique_ptr<uint8_t[]>  vram_ptr;