diff --git a/Makefile b/Makefile
index efa761fd..ecc3fd4d 100644
--- a/Makefile
+++ b/Makefile
@@ -44,6 +44,11 @@ clean :
 	rm -rf test.txt a.out *.so *.o *.a *.out tags cyclone icyc scheme/*.o scheme/*.so scheme/*.c scheme/*.meta srfi/*.c srfi/*.meta srfi/*.o srfi/*.so scheme/cyclone/*.o scheme/cyclone/*.so scheme/cyclone/*.c scheme/cyclone/*.meta cyclone.c dispatch.c icyc.c generate-c.c generate-c
 	cd $(EXAMPLE_DIR) ; make clean
 	rm -rf html tests/*.o tests/*.c
+	rm -f tests/srfi-28-tests
+	rm -f tests/srfi-60-tests
+	rm -f tests/srfi-121-tests
+	rm -f tests/srfi-143-tests
+	rm -f tests/array-list-tests
 
 install : libs install-libs install-includes install-bin
 	$(MKDIR) $(DESTDIR)$(DATADIR)
diff --git a/srfi/27.sld b/srfi/27.sld
index b70d637b..ed67b447 100644
--- a/srfi/27.sld
+++ b/srfi/27.sld
@@ -66,12 +66,12 @@
     (define random-source-make-reals
       (case-lambda
         ((s)
-         (random-source-make-reals s (/ m)))
+         (random-source-make-reals s (/ 1.0 m)))
         ((s unit)
          (if (not (< 0.0 unit 1.0))
              (error "unit must be between 0.0 and 1.0 (exclusive), but got " unit))
          (let ((numgen (random-source-make-integers s)))
-           (define r (exact (floor (/ unit))))
+           (define r (exact (floor (/ 1.0 unit))))
            (lambda ()
              (* (numgen r) unit))))))