diff --git a/src/filters.c b/src/filters.c
index 6a74968..902d220 100644
--- a/src/filters.c
+++ b/src/filters.c
@@ -287,5 +287,6 @@ u32_box_blur(const unsigned int* src_buf, const PPM* img, const int radius)
 		}
 	}
 	free(first_pass);
+	free((void*)src_buf);
 	return dst_buf;
 }