diff --git a/hal/max32666.c b/hal/max32666.c
index 859ece302d..a8fbaf117c 100644
--- a/hal/max32666.c
+++ b/hal/max32666.c
@@ -105,8 +105,9 @@ static void RAMFUNCTION icc_disable(void)
 
 static void RAMFUNCTION icc_enable(void)
 {
-    /* Invalidate and re-enable cache */
+    /* Invalidate cache, wait for completion, then re-enable */
     ICC0_INVALIDATE = 1;
+    while (!(ICC0_CTRL & ICC_CTRL_RDY)) {}
     ICC0_CTRL |= ICC_CTRL_EN;
     while (!(ICC0_CTRL & ICC_CTRL_RDY)) {}
 }
@@ -325,6 +326,14 @@ void hal_init(void)
     FLC0_CLKDIV = FLC_CLKDIV_VALUE;
     FLC1_CLKDIV = FLC_CLKDIV_VALUE;
 
+    /* Point VTOR at our vector table so faults hit our handlers */
+    *(volatile uint32_t *)0xE000ED08 = 0x10000000;
+
+    /* Disable the ICC read buffer via TME before enabling the cache */
+    TME_CTRL = 1;
+    SIR_TRIM_ICC = SIR_TRIM_ICC_RB_DIS;
+    TME_CTRL = 0;
+
     /* Enable instruction cache */
     icc_enable();
 
diff --git a/hal/max32666.h b/hal/max32666.h
index 94f1d734fb..d5fe8d2b2a 100644
--- a/hal/max32666.h
+++ b/hal/max32666.h
@@ -170,6 +170,11 @@
 #define ICC_CTRL_EN             (1UL << 0)          /* Cache enable */
 #define ICC_CTRL_RDY            (1UL << 16)         /* Cache ready */
 
+/* Test mode / trim registers */
+#define TME_CTRL                (*(volatile uint32_t *)0x40000C00UL)
+#define SIR_TRIM_ICC            (*(volatile uint32_t *)0x4000040CUL)
+#define SIR_TRIM_ICC_RB_DIS     (1UL << 6)          /* Read buffer disable */
+
 /* ============== WDT - Watchdog Timer ============== */
 /* MSDK: wdt_regs.h */
 #define WDT0_BASE               0x40003000UL
diff --git a/src/libwolfboot.c b/src/libwolfboot.c
index 62fa63e55c..0ac7bd1154 100644
--- a/src/libwolfboot.c
+++ b/src/libwolfboot.c
@@ -178,7 +178,8 @@ int wolfBoot_initialize_encryption(void)
 #undef WOLFBOOT_FIXED_PARTITIONS
 #endif
 
-#if defined(EXT_FLASH) && !defined(WOLFBOOT_NO_PARTITIONS)
+#if defined(EXT_FLASH) && !defined(WOLFBOOT_NO_PARTITIONS) && \
+    !defined(CUSTOM_PARTITION_TRAILER)
 static uint32_t ext_cache;
 #endif
 
diff --git a/src/update_flash.c b/src/update_flash.c
index 0cfeaab62e..f40129d855 100644
--- a/src/update_flash.c
+++ b/src/update_flash.c
@@ -914,6 +914,9 @@ static int RAMFUNCTION wolfBoot_update(int fallback_allowed)
     int fallback_image = 0;
 #ifndef DISABLE_BACKUP
     int rollback_needed = 0;
+#ifdef CUSTOM_PARTITION_TRAILER
+    (void)rollback_needed;
+#endif
     int bootStateRet = -1;
     uint8_t bootState = 0;
 #endif
@@ -1444,7 +1447,7 @@ void RAMFUNCTION wolfBoot_start(void)
     int bootRet;
 #ifndef WOLFBOOT_SELF_UPDATE_MONOLITHIC
     int updateRet;
-#ifndef DISABLE_BACKUP
+#if !defined(DISABLE_BACKUP) && !defined(CUSTOM_PARTITION_TRAILER)
     int resumedFinalErase;
 #endif
     uint8_t bootState;