diff --git a/garlic/stages/experiment.nix b/garlic/stages/experiment.nix
index ec5f752..b50fdec 100644
--- a/garlic/stages/experiment.nix
+++ b/garlic/stages/experiment.nix
@@ -31,7 +31,7 @@ stdenv.mkDerivation {
     #!/bin/sh
 
     if [ -z "\$GARLIC_OUT" ]; then
-      >&2 echo "GARLIC_OUT not defined, aborting"
+      >&2 echo "experiment: GARLIC_OUT not defined, aborting"
       exit 1
     fi
 
@@ -40,7 +40,7 @@ stdenv.mkDerivation {
     export GARLIC_EXPERIMENT=$(basename $out)
 
     if [ -e "\$GARLIC_EXPERIMENT" ]; then
-      >&2 echo "skipping, experiment exists: \$(pwd)/\$GARLIC_EXPERIMENT"
+      >&2 echo "experiment: skipping, directory exists: \$GARLIC_EXPERIMENT"
       exit 0
     fi
 
@@ -49,7 +49,7 @@ stdenv.mkDerivation {
     cd "\$GARLIC_EXPERIMENT"
     ${unitsLinks}
 
-    echo "Running experiment \$GARLIC_EXPERIMENT"
+    >&2 echo "experiment: running \$GARLIC_EXPERIMENT"
 
     # This is an experiment formed by the following units:
     ${unitsString}
diff --git a/garlic/stages/unit.nix b/garlic/stages/unit.nix
index 72ee52e..babf39a 100644
--- a/garlic/stages/unit.nix
+++ b/garlic/stages/unit.nix
@@ -56,17 +56,17 @@ stdenv.mkDerivation {
     ${desc}
 
     if [ -z "\$GARLIC_OUT" ]; then
-      >&2 echo "GARLIC_OUT not defined, aborting"
+      >&2 echo "unit: GARLIC_OUT not defined, aborting"
       exit 1
     fi
 
     if [ -z "\$GARLIC_EXPERIMENT" ]; then
-      >&2 echo "GARLIC_EXPERIMENT not defined, aborting"
+      >&2 echo "unit: GARLIC_EXPERIMENT not defined, aborting"
       exit 1
     fi
 
     if [ -z "\$GARLIC_INDEX" ]; then
-      >&2 echo "GARLIC_INDEX not defined, aborting"
+      >&2 echo "unit: GARLIC_INDEX not defined, aborting"
       exit 1
     fi
 
@@ -86,7 +86,7 @@ stdenv.mkDerivation {
       "\$GARLIC_INDEX/${safeExpName}"
 
     if [ -e "\$GARLIC_UNIT" ]; then
-      >&2 echo "skipping, unit path already exists: \$GARLIC_UNIT"
+      >&2 echo "unit: skipping, already exists: \$GARLIC_UNIT"
       exit 0
     fi