diff --git a/e/emacs/SlackBuild b/e/emacs/SlackBuild
index 23449388..b97b66c1 100755
--- a/e/emacs/SlackBuild
+++ b/e/emacs/SlackBuild
@@ -51,6 +51,8 @@ fi
 VERSION=${VERSION:-latest}
 UI=${UI:-pgtk}        # pgtk or x11 or nox
 
+PREFIX=${PREFIX:-/usr}
+
 REPOSITORY=/home/installs/SlackBuilds/_repositories/$PKGNAM
 
 rm -rf "$PKG"
@@ -131,13 +133,13 @@ GWH_OPTIONS="--with-tree-sitter \
   --enable-link-time-optimization \
   --with-native-compilation=aot"
 
-CONFIGURE_OPTIONS="--prefix=/usr \
+CONFIGURE_OPTIONS="--prefix=${PREFIX} \
   --sysconfdir=/etc \
   --localstatedir=/var \
   --program-prefix="" \
   --program-suffix="" \
-  --mandir=/usr/man \
-  --infodir=/usr/info \
+  --mandir=${PREFIX}/man \
+  --infodir=${PREFIX}/info \
   --without-gconf \
   --without-gsettings \
   --without-android \
@@ -181,35 +183,35 @@ if [ -d "$PKG/var/games/emacs" ]; then
 fi
 
 # This avoids a collision with Exuberant Ctags...
-mv "$PKG/usr/bin/ctags" "$PKG/usr/bin/ctags-emacs"
-if [ -r "$PKG/usr/man/man1/ctags.1" ]; then
-  mv "$PKG/usr/man/man1/ctags.1" "$PKG/usr/man/man1/ctags-emacs.1"
-elif [ -r "$PKG/usr/man/man1/ctags.1.gz" ]; then
-  mv "$PKG/usr/man/man1/ctags.1.gz" "$PKG/usr/man/man1/ctags-emacs.1.gz"
+mv "$PKG${PREFIX}/bin/ctags" "$PKG${PREFIX}/bin/ctags-emacs"
+if [ -r "$PKG${PREFIX}/man/man1/ctags.1" ]; then
+  mv "$PKG${PREFIX}/man/man1/ctags.1" "$PKG${PREFIX}/man/man1/ctags-emacs.1"
+elif [ -r "$PKG${PREFIX}/man/man1/ctags.1.gz" ]; then
+  mv "$PKG${PREFIX}/man/man1/ctags.1.gz" "$PKG${PREFIX}/man/man1/ctags-emacs.1.gz"
 fi
 
 find -0 "$PKG" | xargs file | grep -e "executable" -e "shared object" \
   | grep ELF | cut -f 1 -d : | xargs strip --strip-unneeded 2> /dev/null
 
-( cd "$PKG/usr/man" || exit 1
+( cd "$PKG${PREFIX}/man" || exit 1
   find . -type f -exec gzip -9 {} \+
   for i in $(find . -type l) ; do ln -s $( readlink $i ).gz $i.gz ; rm $i ; done
 )
 
-( cd "$PKG/usr/info" || exit 1
+( cd "$PKG${PREFIX}/info" || exit 1
   rm -f dir
   gzip -9 ./*
 )
 
-mkdir -p "$PKG/usr/doc/$PKGNAM"
+mkdir -p "$PKG${PREFIX}/doc/$PKGNAM"
 cp -a \
   AUTHORS* COPYING* INSTALL* README* ChangeLog* \
-  "$PKG/usr/doc/$PKGNAM"
+  "$PKG${PREFIX}/doc/$PKGNAM"
 
 # Link the latest NEWS file:
-( cd "$PKG/usr/doc/$PKGNAM" || exit 1
-  if [ -r "$PKG/usr/share/emacs/$VERSION/etc/NEWS" ]; then
-    ln -sf "/usr/share/emacs/$VERSION/etc/NEWS" .
+( cd "$PKG${PREFIX}/doc/$PKGNAM" || exit 1
+  if [ -r "$PKG${PREFIX}/share/emacs/$VERSION/etc/NEWS" ]; then
+    ln -sf "${PREFIX}/share/emacs/$VERSION/etc/NEWS" .
   fi
 )
 
diff --git a/l/basu/SlackBuild b/l/basu/SlackBuild
index fcb73be8..6afdcb74 100755
--- a/l/basu/SlackBuild
+++ b/l/basu/SlackBuild
@@ -36,7 +36,7 @@ cd $TMP/$PRGNAM/
 [ "x$VERSION" == "xtrunk" ] && VERSION="git_r$( cd $REPOSITORY && git rev-list --count HEAD )" || git checkout $VERSION
 
 meson build/
-meson configure --prefix /usr --mandir /usr/man/ build/
+meson configure --prefix ${PREFIX} --mandir ${PREFIX}/man/ build/
 ninja -C build/
 cd build/
 meson install --destdir=$PKG
diff --git a/l/fmt/SlackBuild b/l/fmt/SlackBuild
index a52cbc72..180705a2 100755
--- a/l/fmt/SlackBuild
+++ b/l/fmt/SlackBuild
@@ -55,7 +55,7 @@ chown -R root:root *
 
 find $PKG -name \.git\* -exec rm -fr {} \;
 
-[ -d $PKG/usr/man ] && find $PKG/usr/man -type f -name "*.?" -exec gzip -9f {} \;
+[ -d $PKG${PREFIX}/man ] && find $PKG${PREFIX}/man -type f -name "*.?" -exec gzip -9f {} \;
 
 # # Strip binaries
 # cd $PKG
diff --git a/l/hinnant-date/SlackBuild b/l/hinnant-date/SlackBuild
index 45f425a0..ace94b73 100755
--- a/l/hinnant-date/SlackBuild
+++ b/l/hinnant-date/SlackBuild
@@ -20,8 +20,6 @@ REPOSITORY=/home/installs/SlackBuilds/_repositories/$PRGNAM
 
 PREFIX=/usr
 
-SLCKFLAGS=" -O "
-
 # nettoyage préalable
 rm -fr $PKG $TMP/$PRGNAM
 
@@ -62,7 +60,7 @@ chown -R root:root *
 
 find $PKG -name \.git\* -exec rm -fr {} \;
 
-[ -d $PKG/usr/man ] && find $PKG/usr/man -type f -name "*.?" -exec gzip -9f {} \;
+[ -d $PKG${PREFIX}/man ] && find $PKG${PREFIX}/man -type f -name "*.?" -exec gzip -9f {} \;
 
 # # Strip binaries
 # cd $PKG
diff --git a/l/raylib/SlackBuild b/l/raylib/SlackBuild
index 83537cf0..93ce0af5 100755
--- a/l/raylib/SlackBuild
+++ b/l/raylib/SlackBuild
@@ -18,9 +18,6 @@ ARCH=$(uname -m)
 REPOSITORY=/home/installs/SlackBuilds/_repositories/$PRGNAM
 PREFIX=/usr
 
-EMACS=$(basename $(ls /usr/bin/emacs-2*))
-EMACS_VERSION=$(echo "$EMACS" | grep -o "\-[0-9\.]*\-" | tr -d - | head -n1)
-
 # nettoyage préalable
 rm -fr $PKG $TMP/$PRGNAM
 
diff --git a/l/sdl12-compat/SlackBuild b/l/sdl12-compat/SlackBuild
index 1f48ebff..fe3a4ed3 100755
--- a/l/sdl12-compat/SlackBuild
+++ b/l/sdl12-compat/SlackBuild
@@ -64,7 +64,7 @@ chown -R root:root ./*
 
 find . -name \.git\* -exec rm -fr {} \;
 
-[ -d ./usr/man ] && find ./usr/man -type f -name "*.?" -exec gzip -9f {} \;
+[ -d .${PREFIX}/man ] && find .${PREFIX}/man -type f -name "*.?" -exec gzip -9f {} \;
 
 # # Strip binaries
 # cd $PKG
diff --git a/l/seatd/SlackBuild b/l/seatd/SlackBuild
index 9ebb6e61..2c2b1fdf 100755
--- a/l/seatd/SlackBuild
+++ b/l/seatd/SlackBuild
@@ -34,7 +34,7 @@ cd $TMP/$PRGNAM/
 [ "x$VERSION" == "x" ] && VERSION=trunk
 [ "x$VERSION" == "xtrunk" ] && VERSION="git_r$(git rev-list --count HEAD)_$(git log -1 --format=%h)" || git checkout $VERSION
 
-meson setup --prefix /usr --mandir /usr/man/ build/
+meson setup --prefix ${PREFIX} --mandir ${PREFIX}/man/ build/
 ninja -C build/
 cd build/
 meson install --destdir=$PKG
diff --git a/l/spdlog/SlackBuild b/l/spdlog/SlackBuild
index 1d82de8e..66d08b2e 100755
--- a/l/spdlog/SlackBuild
+++ b/l/spdlog/SlackBuild
@@ -56,7 +56,7 @@ chown -R root:root *
 
 find $PKG -name \.git\* -exec rm -fr {} \;
 
-[ -d $PKG/usr/man ] && find $PKG/usr/man -type f -name "*.?" -exec gzip -9f {} \;
+[ -d $PKG${PREFIX}/man ] && find $PKG${PREFIX}/man -type f -name "*.?" -exec gzip -9f {} \;
 
 # # Strip binaries
 # cd $PKG
diff --git a/y/FlashBack/SlackBuild b/y/FlashBack/SlackBuild
index d505a2d2..9c174630 100755
--- a/y/FlashBack/SlackBuild
+++ b/y/FlashBack/SlackBuild
@@ -10,6 +10,7 @@ VERSION=${VERSION:-1.0}
 ARCH=${ARCH:-${ARCH:-dosbox}}
 BUILD=${BUILD:-1}
 
+PREFIX=${PREFIX:-/usr}
 
 PKG=$TMP/pkg-$PRGNAM
 
@@ -18,15 +19,15 @@ rm -rf $PKG $TMP/${PRGNAM}-${VERSION}
 mkdir -p $TMP
 cd $TMP
 
-mkdir -p $PKG/usr/games/ $PKG/usr/share/games/
-cd $PKG/usr/share/games
+mkdir -p $PKG${PREFIX}/games/ $PKG${PREFIX}/share/games/
+cd $PKG${PREFIX}/share/games
 # [ ! -e $CWD/flashback-x86_64.tar.gz ] & wget -c -O $CWD/flashback-x86_64.tar.gz https://lutris.net/files/games/flashback/flashback-x86_64.tar.gz
 # tar xvf $CWD/flashback-x86_64.tar.gz
 # mv flashback FlashBack
 # https://cors.archive.org/cors/msdos_Flashback_-_The_Quest_for_Identity_1993/Flashback_-_The_Quest_for_Identity_1993.zip
 tar xf $CWD/FlashBack.tar.bz2
 cd FlashBack
-chmod a+w /usr/share/games/FlashBack/DATA/*
+chmod a+w ${PREFIX}/share/games/FlashBack/DATA/*
 
 cat <<EOF > dosbox.config
 [sdl]
@@ -137,23 +138,23 @@ dpmi=true
 
 [autoexec]
 # Lines in this section will be run at startup.
-mount f /usr/share/games/FlashBack
+mount f ${PREFIX}/share/games/FlashBack
 f:
 FB.EXE
 exit
 EOF
 
-cd $PKG/usr/games/
+cd $PKG${PREFIX}/games/
 cat <<EOF > flashback.sh
 #!/bin/bash
-dosbox -conf /usr/share/games/FlashBack/dosbox.config \$*
+dosbox -conf ${PREFIX}/share/games/FlashBack/dosbox.config \$*
 EOF
 chmod +x flashback.sh
 
 chown -R root:root $PKG/*
-chmod -R go-w $PKG/usr/share/games/FlashBack/
-chmod 666 $PKG/usr/share/games/FlashBack/DATA/*
-chmod a+w $PKG/usr/share/games/FlashBack/DATA/{GLOBAL.FIB,DATA/FB_TXT.FNT,DATA/LOGOS.POL}
+chmod -R go-w $PKG${PREFIX}/share/games/FlashBack/
+chmod 666 $PKG${PREFIX}/share/games/FlashBack/DATA/*
+chmod a+w $PKG${PREFIX}/share/games/FlashBack/DATA/{GLOBAL.FIB,DATA/FB_TXT.FNT,DATA/LOGOS.POL}
 
 mkdir -p $PKG/install
 
@@ -175,7 +176,7 @@ ${PRGNAM}:
 ${PRGNAM}:
 ${PRGNAM}:
 ${PRGNAM}:
-${PRGNAM}: see /usr/doc/${PRGNAM}-${VERSION} for more.
+${PRGNAM}: see ${PREFIX}/doc/${PRGNAM}-${VERSION} for more.
 ${PRGNAM}:
 EOF
 
diff --git a/y/cboard/SlackBuild b/y/cboard/SlackBuild
index 502af8e0..c89f7a9e 100755
--- a/y/cboard/SlackBuild
+++ b/y/cboard/SlackBuild
@@ -18,7 +18,7 @@ OUTPUT=/tmp
 
 REPOSITORY=/home/installs/SlackBuilds/_repositories/$PRGNAM
 
-PREFIX=/usr
+PREFIX=${PREFIX:-/usr}
 
 # Cleaning
 rm -fr $PKG $TMP/$PRGNAM
diff --git a/y/eliot/SlackBuild b/y/eliot/SlackBuild
index 67ed2ed4..52691ed9 100755
--- a/y/eliot/SlackBuild
+++ b/y/eliot/SlackBuild
@@ -7,6 +7,8 @@ VERSION=${VERSION:-latest}
 BUILD=${BUILD:-3}
 TAG=${TAG:-gwh}
 
+PREFIX=${PREFIX:-/usr}
+
 if [ -z "$ARCH" ]; then
   case "$( uname -m )" in
     i?86) ARCH=i486 ;;
@@ -63,10 +65,10 @@ CFLAGS="$SLKCFLAGS" \
 CFLAGS="$SLKCFLAGS" \
       CXXFLAGS="$SLKCFLAGS" \
       ./configure \
-      --prefix=/usr \
+      --prefix=${PREFIX} \
       --sysconfdir=/etc \
-      --mandir=/usr/man \
-      --libdir=/usr/lib$(uname -m | grep -o 64) \
+      --mandir=${PREFIX}/man \
+      --libdir=${PREFIX}/lib$(uname -m | grep -o 64) \
       --build=$ARCH-slackware-linux \
       --host=$ARCH-slackware-linux
 
@@ -76,12 +78,12 @@ make install DESTDIR=$PKG
 find $PKG -print0 | xargs -0 file | grep -e "executable" -e "shared object" | grep ELF \
     | cut -f 1 -d : | xargs strip --strip-unneeded 2> /dev/null || true
 
-# find $PKG/usr/man -type f -exec gzip -9 {} \;
-# for i in $( find $PKG/usr/man -type l ) ; do ln -s $( readlink $i ).gz $i.gz ; rm $i ; done
+# find $PKG${PREFIX}/man -type f -exec gzip -9 {} \;
+# for i in $( find $PKG${PREFIX}/man -type l ) ; do ln -s $( readlink $i ).gz $i.gz ; rm $i ; done
 
-mkdir -p $PKG/usr/doc/$PRGNAM
-cp -R AUTHORS ChangeLog COPYING* INSTALL LGPL-2.0.txt NEWS README THANKS TODO $PKG/usr/doc/$PRGNAM
-cat <<EOF > $PKG/usr/doc/$PRGNAM/gen-ODS9-dawg.bash
+mkdir -p $PKG${PREFIX}/doc/$PRGNAM
+cp -R AUTHORS ChangeLog COPYING* INSTALL LGPL-2.0.txt NEWS README THANKS TODO $PKG${PREFIX}/doc/$PRGNAM
+cat <<EOF > $PKG${PREFIX}/doc/$PRGNAM/gen-ODS9-dawg.bash
 #!/bin/bash
 
 if [ \$UID = 0 ]; then
@@ -101,14 +103,14 @@ done
 echo
 
 echo "Generating dictionary…"
-/usr/bin/compdic -d 'ODS 9.0' -l /tmp/letters.txt -i /tmp/ods9.txt -o /tmp/ods9.dawg
+${PREFIX}/bin/compdic -d 'ODS 9.0' -l /tmp/letters.txt -i /tmp/ods9.txt -o /tmp/ods9.dawg
 
 echo "Installing dictionary into ~/.config/eliot/ods9.dawg…"
 mkdir -p ~/.config/eliot/
 [ -e ~/.config/eliot/ods9.dawg ] && mv ~/.config/eliot/ods9.dawg ~/.config/eliot/ods9.dawg.orig
 cp /tmp/ods9.dawg ~/.config/eliot/ods9.dawg
 EOF
-chmod +x $PKG/usr/doc/$PRGNAM/gen-ODS9-dawg.bash
+chmod +x $PKG${PREFIX}/doc/$PRGNAM/gen-ODS9-dawg.bash
 
 mkdir -p $PKG/install
 cat <<EOF > $PKG/install/slack-desc
@@ -128,7 +130,7 @@ $PRGNAM:
 $PRGNAM:
 $PRGNAM:
 $PRGNAM:
-$PRGNAM: (see helper script /usr/doc/$PRGNAM/gen-ODS9-dawg.bash)
+$PRGNAM: (see helper script ${PREFIX}/doc/$PRGNAM/gen-ODS9-dawg.bash)
 $PRGNAM:
 $PRGNAM: https://www.nongnu.org/eliot/fr/index.html
 EOF