diff --git a/easybuild/easyconfigs/b/BLAST+/BLAST+-2.13.0-gompi-2022a.eb b/easybuild/easyconfigs/b/BLAST+/BLAST+-2.13.0-gompi-2022a.eb
index d47478daa91..6e288488900 100644
--- a/easybuild/easyconfigs/b/BLAST+/BLAST+-2.13.0-gompi-2022a.eb
+++ b/easybuild/easyconfigs/b/BLAST+/BLAST+-2.13.0-gompi-2022a.eb
@@ -41,7 +41,7 @@ dependencies = [
 ]
 
 # remove line that prepends system paths to $PATH from configure script
-preconfigopts = 'sed -i "s|^PATH=\(.*\)$|#PATH=\1 |" %(start_dir)s/src/build-system/configure && '
+preconfigopts = r'sed -i "s|^PATH=\(.*\)$|#PATH=\1 |" %(start_dir)s/src/build-system/configure && '
 
 configopts = "--with-64 --with-z=$EBROOTZLIB --with-bz2=$EBROOTBZIP2 "
 configopts += "--with-pcre=$EBROOTPCRE --with-boost=$EBROOTBOOST "
diff --git a/easybuild/easyconfigs/b/BLAST+/BLAST+-2.14.0-gompi-2022b.eb b/easybuild/easyconfigs/b/BLAST+/BLAST+-2.14.0-gompi-2022b.eb
index 101e618f606..0733a8e3e70 100644
--- a/easybuild/easyconfigs/b/BLAST+/BLAST+-2.14.0-gompi-2022b.eb
+++ b/easybuild/easyconfigs/b/BLAST+/BLAST+-2.14.0-gompi-2022b.eb
@@ -41,7 +41,7 @@ dependencies = [
 ]
 
 # remove line that prepends system paths to $PATH from configure script
-preconfigopts = 'sed -i "s|^PATH=\(.*\)$|#PATH=\1 |" %(start_dir)s/src/build-system/configure && '
+preconfigopts = r'sed -i "s|^PATH=\(.*\)$|#PATH=\1 |" %(start_dir)s/src/build-system/configure && '
 
 configopts = "--with-64 --with-z=$EBROOTZLIB --with-bz2=$EBROOTBZIP2 "
 configopts += "--with-pcre=$EBROOTPCRE --with-boost=$EBROOTBOOST "
diff --git a/easybuild/easyconfigs/b/BLAST+/BLAST+-2.14.1-gompi-2023a.eb b/easybuild/easyconfigs/b/BLAST+/BLAST+-2.14.1-gompi-2023a.eb
index f736a3f4f0f..02971854e19 100644
--- a/easybuild/easyconfigs/b/BLAST+/BLAST+-2.14.1-gompi-2023a.eb
+++ b/easybuild/easyconfigs/b/BLAST+/BLAST+-2.14.1-gompi-2023a.eb
@@ -41,7 +41,7 @@ dependencies = [
 ]
 
 # remove line that prepends system paths to $PATH from configure script
-preconfigopts = 'sed -i "s|^PATH=\(.*\)$|#PATH=\1 |" %(start_dir)s/src/build-system/configure && '
+preconfigopts = r'sed -i "s|^PATH=\(.*\)$|#PATH=\1 |" %(start_dir)s/src/build-system/configure && '
 
 configopts = "--with-64 --with-z=$EBROOTZLIB --with-bz2=$EBROOTBZIP2 "
 configopts += "--with-pcre=$EBROOTPCRE --with-boost=$EBROOTBOOST "