diff --git a/basis/compiler/cfg/builder/builder-tests.factor b/basis/compiler/cfg/builder/builder-tests.factor
index 2c472bc0ff..412451f640 100644
--- a/basis/compiler/cfg/builder/builder-tests.factor
+++ b/basis/compiler/cfg/builder/builder-tests.factor
@@ -179,4 +179,9 @@ IN: compiler.cfg.builder.tests
 [ f ] [
     [ { byte-array fixnum } declare set-alien-unsigned-1 ]
     [ ##set-alien-integer-1? ] contains-insn?
+] unit-test
+
+[ f ] [
+    [ 1000 [ ] times ]
+    [ [ ##peek? ] [ ##replace? ] bi or ] contains-insn?
 ] unit-test
\ No newline at end of file
diff --git a/basis/math/intervals/intervals-tests.factor b/basis/math/intervals/intervals-tests.factor
index a2bdf6d98f..3b062ade17 100644
--- a/basis/math/intervals/intervals-tests.factor
+++ b/basis/math/intervals/intervals-tests.factor
@@ -23,6 +23,9 @@ IN: math.intervals.tests
 
 [ T{ interval f { 1 t } { 1 t } } ] [ 1 [a,a] ] unit-test
 
+[ 1 0/0. [a,b] ] must-fail
+[ 0/0. 1 [a,b] ] must-fail
+
 [ t ] [ { 3 t } { 3 f } endpoint< ] unit-test
 [ t ] [ { 2 f } { 3 f } endpoint< ] unit-test
 [ f ] [ { 3 f } { 3 t } endpoint< ] unit-test
@@ -350,6 +353,10 @@ comparison-ops [
 
 [ t ] [ full-interval interval-abs [0,inf] = ] unit-test
 
+[ t ] [ [0,inf] interval-abs [0,inf] = ] unit-test
+
+[ t ] [ empty-interval interval-abs empty-interval = ] unit-test
+
 [ t ] [ [0,inf] interval-sq [0,inf] = ] unit-test
 
 ! Test that commutative interval ops really are