diff --git a/prism/Makefile b/prism/Makefile
index 175cae5c..f1877073 100644
--- a/prism/Makefile
+++ b/prism/Makefile
@@ -550,7 +550,7 @@ clean_doc:
 # Set up version, in particular for building releases
 # Unless VERSION has been passed in (as VERSION=xxx),
 # extract version number from Java code using printversion
-VERSION = $(shell PRISM_SRC_DIR=$(PRISM_SRC_DIR) $(PRISM_SRC_DIR)/scripts/printversion.sh 2> /dev/null)
+VERSION = $(shell $(PRISM_SRC_DIR)/scripts/printversion.sh $(PRISM_SRC_DIR) 2> /dev/null)
 
 # Default branch for building source releases
 BRANCH = master
diff --git a/prism/src/scripts/printversion.sh b/prism/src/scripts/printversion.sh
index 10f87f86..986d93fa 100755
--- a/prism/src/scripts/printversion.sh
+++ b/prism/src/scripts/printversion.sh
@@ -4,13 +4,11 @@
 # based on extraction of the info from Java files.
 # Mirrors what is done (in Java) in prism.getVersion().
 
-# If given, PRISM_SRC_DIR is assumed to point to the
-# "src" directory in a PRISM source distribution. The
-# default is just "src".
+# If given, the first argument to the script is assumed
+# to point to the "src" directory in a PRISM source
+# distribution. The default is just "src".
 
-if [ "$PRISM_SRC_DIR" = "" ]; then
-	PRISM_SRC_DIR=src;
-fi
+PRISM_SRC_DIR="${1:-src}"
 
 if [ -f "$PRISM_SRC_DIR"/prism/Version.java ]; then
 	VERSION_NUM=`grep versionString "$PRISM_SRC_DIR"/prism/Version.java | sed -E 's/[^"]+"([^"]+)"[^"]+/\1/'`