diff --git a/core/main.mk b/core/main.mk
index 1ca02d1..8610492 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -179,7 +179,7 @@
 ifneq ($(EXPERIMENTAL_USE_JAVA8),)
 required_version := "1.8.x"
 required_javac_version := "1.8"
-java_version := $(shell echo '$(java_version_str)' | grep 'openjdk .*[ "]1\.8[\. "$$]')
+java_version := $(shell echo '$(java_version_str)' | grep '[ "]1\.8[\. "$$]')
 javac_version := $(shell echo '$(javac_version_str)' | grep '[ "]1\.8[\. "$$]')
 else # default
 required_version := "1.7.x"