diff --git a/.cargo/config.toml b/.cargo/config.toml
new file mode 100644
index 0000000..a441e63
--- /dev/null
+++ b/.cargo/config.toml
@@ -0,0 +1,2 @@
+[env]
+CFLAGS_x86_64_unknown_linux_gnu = { value = "-Werror -Wundef" }
diff --git a/psm/src/arch/aarch_aapcs64.s b/psm/src/arch/aarch_aapcs64.s
index ee10f8a..b6a2e93 100644
--- a/psm/src/arch/aarch_aapcs64.s
+++ b/psm/src/arch/aarch_aapcs64.s
@@ -3,14 +3,14 @@
 
 .text
 
-#if CFG_TARGET_OS_darwin || CFG_TARGET_OS_macos || CFG_TARGET_OS_ios
+#if defined(CFG_TARGET_OS_darwin) || defined(CFG_TARGET_OS_macos) || defined(CFG_TARGET_OS_ios)
 
 #define GLOBL(fnname) .globl _##fnname
 #define TYPE(fnname)
 #define FUNCTION(fnname) _##fnname
 #define END_FUNCTION(fnname)
 
-#elif CFG_TARGET_OS_windows
+#elif defined(CFG_TARGET_OS_windows)
 
 #define GLOBL(fnname) .globl fnname
 #define TYPE(fnname)
diff --git a/psm/src/arch/arm_aapcs.s b/psm/src/arch/arm_aapcs.s
index 8ab5cae..3a01ae0 100644
--- a/psm/src/arch/arm_aapcs.s
+++ b/psm/src/arch/arm_aapcs.s
@@ -4,7 +4,7 @@
 .text
 .syntax unified
 
-#if CFG_TARGET_OS_darwin || CFG_TARGET_OS_macos || CFG_TARGET_OS_ios
+#if defined(CFG_TARGET_OS_darwin) || defined(CFG_TARGET_OS_macos) || defined(CFG_TARGET_OS_ios)
 
 #define GLOBL(fnname) .globl _##fnname
 #define THUMBTYPE(fnname) .thumb_func _##fnname
diff --git a/psm/src/arch/x86.s b/psm/src/arch/x86.s
index 5eec45c..d4b7b39 100644
--- a/psm/src/arch/x86.s
+++ b/psm/src/arch/x86.s
@@ -4,7 +4,7 @@
 
 .text
 
-#if CFG_TARGET_OS_darwin || CFG_TARGET_OS_macos || CFG_TARGET_OS_ios
+#if defined(CFG_TARGET_OS_darwin) || defined(CFG_TARGET_OS_macos) || defined(CFG_TARGET_OS_ios)
 
 #define GLOBL(fnname) .globl _##fnname
 #define TYPE(fnname)
diff --git a/psm/src/arch/x86_64.s b/psm/src/arch/x86_64.s
index 9a9b531..3c876d0 100644
--- a/psm/src/arch/x86_64.s
+++ b/psm/src/arch/x86_64.s
@@ -4,7 +4,7 @@
 
 .text
 
-#if CFG_TARGET_OS_darwin || CFG_TARGET_OS_macos || CFG_TARGET_OS_ios
+#if defined(CFG_TARGET_OS_darwin) || defined(CFG_TARGET_OS_macos) || defined(CFG_TARGET_OS_ios)
 
 #define GLOBL(fnname) .globl _##fnname
 #define TYPE(fnname)