diff --git a/libavcodec/blockdsp.c b/libavcodec/blockdsp.c
index a35df8c7b10eb176d5c064051d84230e7b5629fd..2c396f1f610ea9ffe5fb0c455325d1ff690167bf 100644
--- a/libavcodec/blockdsp.c
+++ b/libavcodec/blockdsp.c
@@ -35,7 +35,8 @@ static void clear_blocks_8_c(int16_t *blocks)
     memset(blocks, 0, sizeof(int16_t) * 6 * 64);
 }
 
-static void fill_block16_c(uint8_t *block, uint8_t value, int line_size, int h)
+static void fill_block16_c(uint8_t *block, uint8_t value, ptrdiff_t line_size,
+                           int h)
 {
     int i;
 
@@ -45,7 +46,8 @@ static void fill_block16_c(uint8_t *block, uint8_t value, int line_size, int h)
     }
 }
 
-static void fill_block8_c(uint8_t *block, uint8_t value, int line_size, int h)
+static void fill_block8_c(uint8_t *block, uint8_t value, ptrdiff_t line_size,
+                          int h)
 {
     int i;
 
diff --git a/libavcodec/blockdsp.h b/libavcodec/blockdsp.h
index 5b5639f5a68ae56ed4bcde7c134376db5b383159..e555d29b6032f13190b7d42b4a6cabc7f482d53d 100644
--- a/libavcodec/blockdsp.h
+++ b/libavcodec/blockdsp.h
@@ -19,6 +19,7 @@
 #ifndef AVCODEC_BLOCKDSP_H
 #define AVCODEC_BLOCKDSP_H
 
+#include <stddef.h>
 #include <stdint.h>
 
 #include "avcodec.h"
@@ -29,7 +30,7 @@
  * h for op_pixels_func is limited to { width / 2, width },
  * but never larger than 16 and never smaller than 4. */
 typedef void (*op_fill_func)(uint8_t *block /* align width (8 or 16) */,
-                             uint8_t value, int line_size, int h);
+                             uint8_t value, ptrdiff_t line_size, int h);
 
 typedef struct BlockDSPContext {
     void (*clear_block)(int16_t *block /* align 16 */);