diff --git a/fw/wlan_defs.h b/fw/wlan_defs.h
index d81973f8a2c1..d2a55653dd1e 100644
--- a/fw/wlan_defs.h
+++ b/fw/wlan_defs.h
@@ -44,8 +44,49 @@
 #define MAX_SPATIAL_STREAM 3
 #endif
 
-#ifndef CONFIG_160MHZ_SUPPORT
-#define CONFIG_160MHZ_SUPPORT 0 /* default: 160 MHz channels not supported */
+/*
+ * NOTE: The CONFIG_160MHZ_SUPPORT is not used consistently - some code
+ * uses "#ifdef CONFIG_160MHZ_SUPPORT" while other code uses
+ * "#if CONFIG_160MHZ_SUPPORT".
+ * This use is being standardized in the recent versions of code to use
+ * #ifdef, but is being left as is in the legacy code branches.
+ * To minimize impact to legacy code branches, this file internally
+ * converts CONFIG_160MHZ_SUPPORT=0 to having CONFIG_160MHZ_SUPPORT
+ * undefined.
+ * For builds that explicitly set CONFIG_160MHZ_SUPPORT=0, the bottom of
+ * this file restores CONFIG_160MHZ_SUPPORT from being undefined to being 0.
+ */
+// OLD:
+//#ifndef CONFIG_160MHZ_SUPPORT
+//#define CONFIG_160MHZ_SUPPORT 0 /* default: 160 MHz channels not supported */
+//#endif
+// NEW:
+#ifdef CONFIG_160MHZ_SUPPORT
+  /* CONFIG_160MHZ_SUPPORT is explicitly enabled or explicitly disabled */
+  #if !CONFIG_160MHZ_SUPPORT
+    /* CONFIG_160MHZ_SUPPORT is explicitly disabled */
+    /* Change from CONFIG_160MHZ_SUPPORT=0 to CONFIG_160MHZ_SUPPORT=<undef> */
+    #undef CONFIG_160MHZ_SUPPORT
+    /*
+     * Set a flag to indicate this CONFIG_160MHZ_SUPPORT = 0 --> undef
+     * change has been done, so we can undo the change at the bottom
+     * of the file.
+     */
+    #define CONFIG_160MHZ_SUPPORT_UNDEF_WAR
+  #endif
+#else
+  /*
+   * For backwards compatibility, if CONFIG_160MHZ_SUPPORT is not defined,
+   * default it to 0, if this is either a host build or a Rome target build.
+   * This maintains the prior behavior for the host and Rome target builds.
+   */
+  #if defined(AR6320) || !defined(ATH_TARGET)
+    /*
+     * Set a flag to indicate that at the end of the file,
+     * CONFIG_160MHZ_SUPPORT should be set to 0.
+     */
+    #define CONFIG_160MHZ_SUPPORT_UNDEF_WAR
+  #endif
 #endif
 
 #ifndef SUPPORT_11AX
@@ -89,7 +130,7 @@ typedef enum {
     MODE_11AC_VHT20_2G = 11,
     MODE_11AC_VHT40_2G = 12,
     MODE_11AC_VHT80_2G = 13,
-#if CONFIG_160MHZ_SUPPORT
+#ifdef CONFIG_160MHZ_SUPPORT
     MODE_11AC_VHT80_80 = 14,
     MODE_11AC_VHT160   = 15,
 #endif
@@ -129,7 +170,7 @@ typedef enum {
 #endif
 } WLAN_PHY_MODE;
 
-#if CONFIG_160MHZ_SUPPORT == 0
+#ifndef CONFIG_160MHZ_SUPPORT
 A_COMPILE_TIME_ASSERT(
     mode_unknown_value_consistency_Check,
     MODE_UNKNOWN == MODE_UNKNOWN_NO_160MHZ_SUPPORT);
@@ -153,7 +194,7 @@ typedef enum {
     WLAN_11AG_CAPABILITY  = 3,
 } WLAN_CAPABILITY;
 
-#if CONFIG_160MHZ_SUPPORT
+#ifdef CONFIG_160MHZ_SUPPORT
 #define IS_MODE_VHT(mode) (((mode) == MODE_11AC_VHT20) || \
         ((mode) == MODE_11AC_VHT40)     || \
         ((mode) == MODE_11AC_VHT80)     || \
@@ -450,7 +491,7 @@ typedef struct {
  * for all targets, but until this is complete, the WHAL_RC_INIT_RC_MASKS def
  * will be maintained here in its old location.
  */
-#if CONFIG_160MHZ_SUPPORT == 0
+#ifndef CONFIG_160MHZ_SUPPORT
 #define WHAL_RC_INIT_RC_MASKS(_rm) do {                                     \
         _rm[WHAL_RC_MASK_IDX_NON_HT] = A_RATEMASK_OFDM_CCK;                 \
         _rm[WHAL_RC_MASK_IDX_HT_20] = A_RATEMASK_HT_20;                     \
@@ -930,4 +971,13 @@ typedef enum {
     WLAN_DBG_DATA_STALL_RECOVERY_CONNECT_SSR,
 } wlan_dbg_data_stall_recovery_type_e;
 
+/*
+ * NOTE: If necessary, restore the explicit disabling of CONFIG_160MHZ_SUPPORT
+ * See the corresponding comment + pre-processor block at the top of the file.
+ */
+#ifdef CONFIG_160MHZ_SUPPORT_UNDEF_WAR
+    #define CONFIG_160MHZ_SUPPORT 0
+    #undef CONFIG_160MHZ_SUPPORT_UNDEF_WAR
+#endif
+
 #endif /* __WLANDEFS_H__ */