diff --git a/07-matrix_experiment/cpp/Makefile b/07-matrix_experiment/cpp/Makefile
index ab0539e2c28b67a2ed9735f41a2e986606d2c122..ce3b51d23eaf59a70e34b7bcc6d3a783a9bcaa51 100644
--- a/07-matrix_experiment/cpp/Makefile
+++ b/07-matrix_experiment/cpp/Makefile
@@ -21,6 +21,6 @@ matrix_experiment_real: matrix_transpose.h matrix_tests.h matrix_experiment_real
 	$(CXX) $(CPPFLAGS) $(CXXFLAGS) matrix_experiment_real.cpp -o $@
 
 .PHONY: clean
-clean:
+clean::
 	rm -f matrix_experiment_sim matrix_experiment_real
 	rm -rf out
diff --git a/07-matrix_experiment/cpp/matrix_experiment_real.cpp b/07-matrix_experiment/cpp/matrix_experiment_real.cpp
index 3d2a28aea1f8bfd6d74c1d2480e993cb5ea94048..f46c38acc3354119015eafa61ac47253027e5ffd 100644
--- a/07-matrix_experiment/cpp/matrix_experiment_real.cpp
+++ b/07-matrix_experiment/cpp/matrix_experiment_real.cpp
@@ -5,7 +5,7 @@
 #include <cmath>
 #include <iostream>
 
-#include <time.h>   // FIXME
+#include <time.h>
 
 using namespace std;
 
diff --git a/07-matrix_experiment/cpp/matrix_experiment_sim.cpp b/07-matrix_experiment/cpp/matrix_experiment_sim.cpp
index 5eca7abdb4737e2a8c91419674f05ff2e7013e35..316db527d089075e24dd4707e9f53078989a5a86 100644
--- a/07-matrix_experiment/cpp/matrix_experiment_sim.cpp
+++ b/07-matrix_experiment/cpp/matrix_experiment_sim.cpp
@@ -6,7 +6,7 @@
 #include <string>
 #include <iostream>
 
-#include <time.h>   // FIXME
+#include <time.h>
 
 using namespace std;
 
diff --git a/07-matrix_experiment/python/Makefile b/07-matrix_experiment/python/Makefile
index 6ae85a911a8e15919075926571af214c8c2e2657..26bbb0173f30893c9a5bf546be30b8a580038fe1 100644
--- a/07-matrix_experiment/python/Makefile
+++ b/07-matrix_experiment/python/Makefile
@@ -13,5 +13,5 @@ out/t-sim-%-smart:
 	./matrix_experiment_sim.py $* smart >$@
 
 .PHONY: clean
-clean:
-	rm -rf out
+clean::
+	rm -rf out __pycache__
diff --git a/07-matrix_experiment/task.md b/07-matrix_experiment/task.md
index 40a2682e5177baa236f0e5dd5170c3691ab0edf9..b6fbb30d3b1cd70ed90b0cbc236a91567da32100 100644
--- a/07-matrix_experiment/task.md
+++ b/07-matrix_experiment/task.md
@@ -29,10 +29,10 @@ proper points will be assigned later.
 
 The test program is given two arguments:
 - Cache type:
-    - `m1024b16` – cache of 1024 items organized in 16-item blocks
-    - `m8192b64` – cache of 8192 items organized in 64-item blocks
-    - `m65536b256` – cache of 65536 items organized on 256-item blocks
-    - `m65536b4096` – cache of 65536 items organized in 4096-item blocks
+    - `m1024-b16` – cache of 1024 items organized in 16-item blocks
+    - `m8192-b64` – cache of 8192 items organized in 64-item blocks
+    - `m65536-b256` – cache of 65536 items organized on 256-item blocks
+    - `m65536-b4096` – cache of 65536 items organized in 4096-item blocks
 - The implementation to test (`smart` or `naive`).
 
 The output of the program contains one line per experiment, which consists of