diff --git a/contrib/gana-update.sh b/contrib/gana-update.sh
index 8fcf18852..db122b9a3 100755
--- a/contrib/gana-update.sh
+++ b/contrib/gana-update.sh
@@ -3,32 +3,32 @@
 # Run from exchange/ main directory.
 set -eu
 
-# Generate taler-error-codes.h in gana and copy it to
-# src/include/taler_error_codes.h
-cd contrib/gana/gnu-taler-error-codes
-make
-cd ../../..
-for n in taler_error_codes.c
-do
-    if ! diff contrib/gana/gnu-taler-error-codes/${n} src/util/${n} > /dev/null
+domake ()
+{
+    # $1 -- dir under contrib/gana/
+    dir="contrib/gana/$1"
+
+    make -C $dir
+}
+
+ensure ()
+{
+    # $1 -- filename
+    # $2 -- src dir under contrib/gana/
+    # $3 -- dst dir under ./
+    fn="$1"
+    src="contrib/gana/$2"
+    dst="./$3"
+
+    if ! diff $src/$fn $dst/$fn > /dev/null
     then
-        cp contrib/gana/gnu-taler-error-codes/$n src/util/$n
+        cp $src/$fn $dst/$fn
     fi
-done
-for n in taler_error_codes.h
-do
-    if ! diff contrib/gana/gnu-taler-error-codes/${n} src/include/${n} > /dev/null
-    then
-        cp contrib/gana/gnu-taler-error-codes/$n src/include/$n
-    fi
-done
-cd contrib/gana/gnu-taler-db-events
-make
-cd ../../..
-for n in taler_dbevents.h
-do
-    if ! diff contrib/gana/gnu-taler-db-events/${n} src/include/${n} > /dev/null
-    then
-        cp contrib/gana/gnu-taler-db-events/$n src/include/$n
-    fi
-done
+}
+
+domake                     gnu-taler-error-codes
+ensure taler_error_codes.c gnu-taler-error-codes src/util
+ensure taler_error_codes.h gnu-taler-error-codes src/include
+
+domake                  gnu-taler-db-events
+ensure taler_dbevents.h gnu-taler-db-events src/include