diff --git a/kandinsky/Makefile b/kandinsky/Makefile
index dc149f5e4..3b729095a 100644
--- a/kandinsky/Makefile
+++ b/kandinsky/Makefile
@@ -8,6 +8,9 @@ kandinsky/src/text.c: kandinsky/src/font.h
 
 font_files = $(addprefix kandinsky/src/, font.h font.c)
 
+# Even though raster will generate both .c and .h files, we don't declare it as
+# such to make. If we did, "make -jN" with N>1 may call "raster" twice.
+
 kandinsky/src/font.h: kandinsky/src/font.c
 kandinsky/src/font.c: kandinsky/fonts/rasterizer
 	@echo "RASTER  $(font_files)"
diff --git a/poincare/Makefile b/poincare/Makefile
index 95f225630..de75416d8 100644
--- a/poincare/Makefile
+++ b/poincare/Makefile
@@ -1,6 +1,10 @@
 SFLAGS += -Ipoincare/include
 objs += $(addprefix poincare/src/, expression.o number.o fraction.o power.o expression_lexer.o expression_parser.o)
 
+# Even though flex and bison will generate both implementation and headers at
+# once, we don't declare it in the Makefile. If we did, "make -jN" with N>1 may
+# call bison or flex twice.
+
 lexer_files = $(addprefix poincare/src/, expression_lexer.cpp expression_lexer.hpp)
 poincare/src/expression_lexer.hpp: poincare/src/expression_lexer.cpp
 poincare/src/expression_lexer.cpp: poincare/src/expression_lexer.l