diff --git a/src/mainboard/system76/addw2/Kconfig b/src/mainboard/system76/addw2/Kconfig
index c4df939331..3b65c0711c 100644
--- a/src/mainboard/system76/addw2/Kconfig
+++ b/src/mainboard/system76/addw2/Kconfig
@@ -26,7 +26,7 @@ config BOARD_SPECIFIC_OPTIONS
 
 config MAINBOARD_DIR
 	string
-	default system76/addw2
+	default "system76/addw2"
 
 config MAINBOARD_PART_NUMBER
 	string
diff --git a/src/mainboard/system76/cml-u/Kconfig b/src/mainboard/system76/cml-u/Kconfig
index 5993e99a71..0b8abcb275 100644
--- a/src/mainboard/system76/cml-u/Kconfig
+++ b/src/mainboard/system76/cml-u/Kconfig
@@ -27,7 +27,7 @@ config BOARD_SPECIFIC_OPTIONS
 
 config MAINBOARD_DIR
 	string
-	default system76/cml-u
+	default "system76/cml-u"
 
 config VARIANT_DIR
 	string
diff --git a/src/mainboard/system76/gaze14/Kconfig b/src/mainboard/system76/gaze14/Kconfig
index 62510c5fa6..e2ae4cdd3f 100644
--- a/src/mainboard/system76/gaze14/Kconfig
+++ b/src/mainboard/system76/gaze14/Kconfig
@@ -24,7 +24,7 @@ config BOARD_SPECIFIC_OPTIONS
 
 config MAINBOARD_DIR
 	string
-	default system76/gaze14
+	default "system76/gaze14"
 
 config VARIANT_DIR
 	string
diff --git a/src/mainboard/system76/gaze15/Kconfig b/src/mainboard/system76/gaze15/Kconfig
index 50fb89b697..f5a5cdaef4 100644
--- a/src/mainboard/system76/gaze15/Kconfig
+++ b/src/mainboard/system76/gaze15/Kconfig
@@ -24,7 +24,7 @@ config BOARD_SPECIFIC_OPTIONS
 
 config MAINBOARD_DIR
 	string
-	default system76/gaze15
+	default "system76/gaze15"
 
 config MAINBOARD_PART_NUMBER
 	string
diff --git a/src/mainboard/system76/kbl-u/Kconfig b/src/mainboard/system76/kbl-u/Kconfig
index 52c580fb50..87b631d83e 100644
--- a/src/mainboard/system76/kbl-u/Kconfig
+++ b/src/mainboard/system76/kbl-u/Kconfig
@@ -25,7 +25,7 @@ config BOARD_SPECIFIC_OPTIONS
 
 config MAINBOARD_DIR
 	string
-	default system76/kbl-u
+	default "system76/kbl-u"
 
 config VARIANT_DIR
 	string
diff --git a/src/mainboard/system76/oryp6/Kconfig b/src/mainboard/system76/oryp6/Kconfig
index b73bc8a995..14eaac0b52 100644
--- a/src/mainboard/system76/oryp6/Kconfig
+++ b/src/mainboard/system76/oryp6/Kconfig
@@ -26,7 +26,7 @@ config BOARD_SPECIFIC_OPTIONS
 
 config MAINBOARD_DIR
 	string
-	default system76/oryp6
+	default "system76/oryp6"
 
 config MAINBOARD_PART_NUMBER
 	string
diff --git a/src/mainboard/system76/thelio-b1/Kconfig b/src/mainboard/system76/thelio-b1/Kconfig
index 99d903eba6..a890ea83b6 100644
--- a/src/mainboard/system76/thelio-b1/Kconfig
+++ b/src/mainboard/system76/thelio-b1/Kconfig
@@ -24,7 +24,7 @@ config BOARD_SPECIFIC_OPTIONS
 
 config MAINBOARD_DIR
 	string
-	default system76/thelio-b1
+	default "system76/thelio-b1"
 
 config MAINBOARD_PART_NUMBER
 	string
diff --git a/src/mainboard/system76/whl-u/Kconfig b/src/mainboard/system76/whl-u/Kconfig
index 39f769e06a..4887a8db79 100644
--- a/src/mainboard/system76/whl-u/Kconfig
+++ b/src/mainboard/system76/whl-u/Kconfig
@@ -27,7 +27,7 @@ config BOARD_SPECIFIC_OPTIONS
 
 config MAINBOARD_DIR
 	string
-	default system76/whl-u
+	default "system76/whl-u"
 
 config VARIANT_DIR
 	string