Index: /issm/trunk-jpl/etc/environment.sh
===================================================================
--- /issm/trunk-jpl/etc/environment.sh	(revision 20327)
+++ /issm/trunk-jpl/etc/environment.sh	(revision 20328)
@@ -96,6 +96,8 @@
 
 PETSC_DIR="$ISSM_DIR/externalpackages/petsc/install"
-export PETSC_DIR
-libpathappend "$PETSC_DIR/lib"
+if [ -d "$PETSC_DIR" ]; then
+	export PETSC_DIR
+	libpathappend "$PETSC_DIR/lib"
+fi
 
 SLEPC_DIR="$ISSM_DIR/externalpackages/slepc/install"