diff --git a/src/matrix.c b/src/matrix.c
index 468b465..e8e7ebd 100644
--- a/src/matrix.c
+++ b/src/matrix.c
@@ -6,53 +6,54 @@
 
 #include <stddef.h>
 
-#define MATRIX_LETTER_TRAIL 4
-
 typedef struct MatrixLetter {
-    Lfsr *lfsr;
     int8_t row;
+    int8_t trail_row;
     uint8_t column;
 } MatrixLetter;
 
 typedef struct MatrixContext {
     Lfsr lfsr;
+    uint8_t trail;
     MatrixLetter letters[80];
 } MatrixContext;
 
-static MatrixContext ctx;
+static MatrixContext mctx;
 
-static void matrixLetter_init(MatrixLetter *ctx, Lfsr *lfsr) {
-    ctx->lfsr = lfsr;
-    ctx->column = lfsr_next(ctx->lfsr) % 80;
-    ctx->row = lfsr_next(ctx->lfsr) % 50 - 50;
+static void matrixLetter_init(MatrixLetter *ctx) {
+    ctx->column = lfsr_next(&mctx.lfsr) % 80;
+    ctx->row = lfsr_next(&mctx.lfsr) % 50 - 50;
+    ctx->trail_row = ctx->row - (lfsr_next(&mctx.lfsr) % mctx.trail + 3);
 }
 
 static void matrixLetter_poll(MatrixLetter *ctx) {
     ctx->row++;
+    ctx->trail_row++;
     if (ctx->row < 0)
         return;
 
-    const uint8_t c = lfsr_next(ctx->lfsr) % 256;
+    const uint8_t c = lfsr_next(&mctx.lfsr) % 256;
     video_put(ctx->column, ctx->row, c);
 
-    if (ctx->row < MATRIX_LETTER_TRAIL)
+    if (ctx->trail_row < 0)
         return;
-    video_put(ctx->column, ctx->row - MATRIX_LETTER_TRAIL, ' ');
+    video_put(ctx->column, ctx->trail_row, ' ');
 }
 
-void matrix_init(void) {
-    lfsr_init(&ctx.lfsr, 1);
+void matrix_init(uint8_t trail) {
+    lfsr_init(&mctx.lfsr, 1);
+    mctx.trail = trail;
 
     // using the same LFSR for different letters makes the randomness
     // not reproducible in case we decide to refactor the number of letters,
     // but that's not an issue we care about at the moment
-    for (size_t i = 0; i < countof(ctx.letters); ++i) {
-        matrixLetter_init(&ctx.letters[i], &ctx.lfsr);
+    for (size_t i = 0; i < countof(mctx.letters); ++i) {
+        matrixLetter_init(&mctx.letters[i]);
     }
 }
 
 void matrix_poll(void) {
-    for (size_t i = 0; i < countof(ctx.letters); ++i) {
-        matrixLetter_poll(&ctx.letters[i]);
+    for (size_t i = 0; i < countof(mctx.letters); ++i) {
+        matrixLetter_poll(&mctx.letters[i]);
     }
-}
\ No newline at end of file
+}
diff --git a/src/matrix.h b/src/matrix.h
index 26088e6..32e343e 100644
--- a/src/matrix.h
+++ b/src/matrix.h
@@ -1,7 +1,9 @@
 #ifndef CEDA_MATRIX_H
 #define CEDA_MATRIX_H
 
-void matrix_init(void);
+#include <stdint.h>
+
+void matrix_init(uint8_t trail);
 void matrix_poll(void);
 
 #endif // CEDA_MATRIX_H