diff --git a/dev-python/graph-tool/graph-tool-2.19.ebuild b/dev-python/graph-tool/graph-tool-2.19.ebuild
index 4c2f61756e878..2976ab9180c52 100644
--- a/dev-python/graph-tool/graph-tool-2.19.ebuild
+++ b/dev-python/graph-tool/graph-tool-2.19.ebuild
@@ -61,7 +61,7 @@ src_prepare() {
 
 src_configure() {
 	local threads
-	has_version dev-libs/boost[threads] && threads="-mt"
+	has_version 'dev-libs/boost[threads]' && threads="-mt"
 
 	configure() {
 		econf \
diff --git a/dev-python/graph-tool/graph-tool-9999.ebuild b/dev-python/graph-tool/graph-tool-9999.ebuild
index 4c2f61756e878..2976ab9180c52 100644
--- a/dev-python/graph-tool/graph-tool-9999.ebuild
+++ b/dev-python/graph-tool/graph-tool-9999.ebuild
@@ -61,7 +61,7 @@ src_prepare() {
 
 src_configure() {
 	local threads
-	has_version dev-libs/boost[threads] && threads="-mt"
+	has_version 'dev-libs/boost[threads]' && threads="-mt"
 
 	configure() {
 		econf \