diff --git a/src/universal/bin/sbt.bat b/src/universal/bin/sbt.bat
index 0bf79a0c7..1f72b990e 100644
--- a/src/universal/bin/sbt.bat
+++ b/src/universal/bin/sbt.bat
@@ -127,7 +127,7 @@ exit /B 1
 
 :copyrt
 if /I "%JAVA_VERSION%" GEQ "9" (
-  set rtexport=%SBT_HOME%java9-rt-export.jar
+  set rtexport="%SBT_HOME%java9-rt-export.jar"
 
   "%_JAVACMD%" %_JAVA_OPTS% %SBT_OPTS% -jar "%rtexport%" --rt-ext-dir > "%TEMP%.\rtext.txt"
   set /p java9_ext= < "%TEMP%.\rtext.txt"