diff --git a/Makefile b/Makefile
index d58082c..8f0d203 100644
--- a/Makefile
+++ b/Makefile
@@ -8,7 +8,7 @@ update: update_test-runner.sh update_assert.sh
 test/assert.sh:
 	echo "fetching assert.sh..." && \
 	curl -s -L -o test/assert.sh \
-		https://raw.github.com/lehmannro/assert.sh/v1.0.2/assert.sh
+		https://raw.github.com/lehmannro/assert.sh/v1.1/assert.sh
 
 remove_assert.sh:
 	( \
diff --git a/stub.sh b/stub.sh
index 9f21a39..e0a5ca3 100644
--- a/stub.sh
+++ b/stub.sh
@@ -401,7 +401,7 @@ __stub_register() {
   eval "STUB_${STUB_NEXT_INDEX}_CALLS=()"
 
   # Increment stub count.
-  ((STUB_NEXT_INDEX++))
+  ((++STUB_NEXT_INDEX))
 }
 
 # Private: Cleans out and removes a stub's call list, and removes stub from
diff --git a/test/__stub_register.test.sh b/test/__stub_register.test.sh
index 6631765..2bb97a6 100755
--- a/test/__stub_register.test.sh
+++ b/test/__stub_register.test.sh
@@ -6,7 +6,7 @@ source "test-helper.sh"
 #
 
 # Sets up stub index, stub call list, and adds stub to index.
-__stub_register "uname"
+__stub_register "uname" || assert_raises "false"
 __stub_register "top"
 assert 'echo ${STUB_INDEX[@]}' 'uname=0 top=1'
 assert 'echo ${STUB_INDEX[0]}' 'uname=0'