diff --git a/src/parse b/src/parse
index 369a14ae..9aa29cb1 100755
--- a/src/parse
+++ b/src/parse
@@ -7,6 +7,13 @@ JACKSON_CORE="${LIBPLCC_LIB}/lib/jackson/jackson-core-${JACKSON_VERSION}.jar"
 JACKSON_DATABIND="${LIBPLCC_LIB}/lib/jackson/jackson-databind-${JACKSON_VERSION}.jar"
 CP="${JACKSON_ANNOTATIONS}:${JACKSON_CORE}:${JACKSON_DATABIND}"
 
+if [[ -z "${CLASSPATH:-}" ]] ; then
+    CLASSPATH="./Java:${CP}"
+    export CLASSPATH
+else
+    CLASSPATH="./Java:${CLASSPATH}:${CP}"
+fi
+
 [ -d Java ] || {
     echo "Java directory missing" >&2
     exit 1
@@ -33,10 +40,10 @@ then
         esac
     done
 
-    if ! java -cp "./Java:${CP}" ParseJsonAst "${ARGS[@]}" ; then
+    if ! java ParseJsonAst "${ARGS[@]}" ; then
         >&2 echo "Did you forget to pass --json_ast to plccmk?"
         exit 1
     fi
-else 
-    java -cp ./Java Parse $*
+else
+    java Parse $*
 fi
diff --git a/src/plccmk b/src/plccmk
index a02113ed..29786849 100755
--- a/src/plccmk
+++ b/src/plccmk
@@ -10,7 +10,13 @@ JACKSON_ANNOTATIONS="${LIBPLCC_LIB}/lib/jackson/jackson-annotations-${JACKSON_VE
 JACKSON_CORE="${LIBPLCC_LIB}/lib/jackson/jackson-core-${JACKSON_VERSION}.jar"
 JACKSON_DATABIND="${LIBPLCC_LIB}/lib/jackson/jackson-databind-${JACKSON_VERSION}.jar"
 CP="${JACKSON_ANNOTATIONS}:${JACKSON_CORE}:${JACKSON_DATABIND}"
-export CLASSPATH=".:${CP}"
+
+if [[ -z "${CLASSPATH:-}" ]] ; then
+        CLASSPATH="${CP}"
+        export CLASSPATH
+else
+        CLASSPATH="${CLASSPATH}:${CP}"
+fi
 
 if [ "$1" = "-c" ];
 then
@@ -43,4 +49,3 @@ $PYTHON3 "$PLCC" $FILES || {
 }
 
 (cd ./Java ; javac *.java)
-
diff --git a/src/rep b/src/rep
index 3a13e173..13eb3a5a 100755
--- a/src/rep
+++ b/src/rep
@@ -1,5 +1,12 @@
 #!/bin/bash
 
+if [[ -z "${CLASSPATH:-}" ]] ; then
+    CLASSPATH="./Java"
+    export CLASSPATH
+else
+    CLASSPATH="./Java:${CLASSPATH}"
+fi
+
 [ -d "${PWD}/Java" ] || {
     echo "Java directory missing" >&2
     exit 1
@@ -10,4 +17,4 @@
     exit 2
 }
 
-java -cp ./Java Rep $*
+java Rep $*
diff --git a/src/scan b/src/scan
index 753a66c4..3397323b 100755
--- a/src/scan
+++ b/src/scan
@@ -1,5 +1,13 @@
 #!/bin/bash
 
+if [[ -z "${CLASSPATH:-}" ]] ; then
+    CLASSPATH="./Java"
+    export CLASSPATH
+else
+    CLASSPATH="./Java:${CLASSPATH}"
+fi
+
+
 [ -d Java ] || {
     echo "Java directory missing" >&2
     exit 1
@@ -10,4 +18,4 @@
     exit 2
 }
 
-java -cp ./Java Scan
+java Scan