diff --git a/core/main.mk b/core/main.mk
index 2d42a14..418c673 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -151,22 +151,26 @@
 endif
 endif
 
+java_version_str := $(shell java -version 2>&1)
+javac_version_str := $(shell javac -version 2>&1)
+
+# Check for the current jdk
 ifeq ($(requires_openjdk), true)
 # The user asked for java7 openjdk, so check that the host
 # java version is really openjdk
-ifeq ($(shell java -version 2>&1 | grep -i openjdk),)
+ifeq ($(shell echo '$(java_version_str)' | grep -i openjdk),)
 $(info ************************************************************)
 $(info You are attempting to build with an unsupported JDK.)
 $(info $(space))
 $(info This build requires OpenJDK, but you are using:)
-$(info $(shell java -version 2>&1 | head -n 2).)
+$(info $(java_version_str).)
 $(info Please follow the machine setup instructions at)
 $(info $(space)$(space)$(space)$(space)https://source.android.com/source/download.html)
 $(info ************************************************************)
 $(error stop)
 endif # java version is not OpenJdk
 else # if requires_openjdk
-ifneq ($(shell java -version 2>&1 | grep -i openjdk),)
+ifneq ($(shell echo '$(java_version_str)' | grep -i openjdk),)
 $(info ************************************************************)
 $(info You are attempting to build with an unsupported JDK.)
 $(info $(space))
@@ -183,13 +187,13 @@
 ifneq ($(EXPERIMENTAL_USE_JAVA7),)
 required_version := "1.7.x"
 required_javac_version := "1.7"
-java_version := $(shell java -version 2>&1 | grep '^java .*[ "]1\.7[\. "$$]' | head -n 1)
-javac_version := $(shell javac -version 2>&1 | grep '[ "]1\.7[\. "$$]' | head -n 1 )
+java_version := $(shell echo '$(java_version_str)' | grep '^java .*[ "]1\.7[\. "$$]' | head -n 1)
+javac_version := $(shell echo '$(javac_version_str)' | grep '[ "]1\.7[\. "$$]' | head -n 1)
 else # if EXPERIMENTAL_USE_JAVA7
 required_version := "1.6.x"
 required_javac_version := "1.6"
-java_version := $(shell java -version 2>&1 | grep '^java .*[ "]1\.6[\. "$$]' | head -n 1)
-javac_version := $(shell javac -version 2>&1 | grep '[ "]1\.6[\. "$$]' | head -n 1)
+java_version := $(shell echo '$(java_version_str)' | grep '^java .*[ "]1\.6[\. "$$]' | head -n 1)
+javac_version := $(shell echo '$(javac_version_str)' | head -n 1 | grep '[ "]1\.6[\. "$$]' | head -n 1)
 endif # if EXPERIMENTAL_USE_JAVA7
 
 ifeq ($(strip $(java_version)),)
@@ -197,7 +201,7 @@
 $(info You are attempting to build with the incorrect version)
 $(info of java.)
 $(info $(space))
-$(info Your version is: $(shell java -version 2>&1 | grep '^java' | head -n 1).)
+$(info Your version is: $(java_version_str).)
 $(info The required version is: $(required_version))
 $(info $(space))
 $(info Please follow the machine setup instructions at)
@@ -212,7 +216,7 @@
 $(info You are attempting to build with the incorrect version)
 $(info of javac.)
 $(info $(space))
-$(info Your version is: $(shell javac -version 2>&1 | grep '^javac' | head -n 1).)
+$(info Your version is: $(javac_version_str).)
 $(info The required version is: $(required_javac_version))
 $(info $(space))
 $(info Please follow the machine setup instructions at)
@@ -221,6 +225,7 @@
 $(error stop)
 endif
 
+
 ifndef BUILD_EMULATOR
 ifeq (darwin,$(HOST_OS))
 GCC_REALPATH = $(realpath $(shell which $(HOST_CC)))