diff --git a/libretro-common/formats/libchdr/libchdr_lzma.c b/libretro-common/formats/libchdr/libchdr_lzma.c
index c947b16298..25fabe3cf4 100644
--- a/libretro-common/formats/libchdr/libchdr_lzma.c
+++ b/libretro-common/formats/libchdr/libchdr_lzma.c
@@ -88,7 +88,7 @@ static void *lzma_fast_alloc(void *p, size_t size)
 	}
 
 	/* alloc a new one and put it into the list */
-	addr = (uint32_t *)malloc(sizeof(uint32_t) * (size + sizeof(uint32_t)));
+	addr = (uint32_t *)malloc(sizeof(uint32_t) * size + sizeof(uintptr_t));
 	if (!addr)
 		return NULL;
 
diff --git a/libretro-common/formats/libchdr/libchdr_zlib.c b/libretro-common/formats/libchdr/libchdr_zlib.c
index 6e4a5dea7d..7e6fe19ac8 100644
--- a/libretro-common/formats/libchdr/libchdr_zlib.c
+++ b/libretro-common/formats/libchdr/libchdr_zlib.c
@@ -263,7 +263,7 @@ voidpf zlib_fast_alloc(voidpf opaque, uInt items, uInt size)
 	}
 
 	/* alloc a new one */
-	ptr = (UINT32 *)malloc(size + sizeof(UINT32));
+	ptr = (UINT32 *)malloc(size + sizeof(uintptr_t));
 	if (!ptr)
 		return NULL;