diff --git a/arch/arm/src/armv7-m/mpu.h b/arch/arm/src/armv7-m/mpu.h
index 5017023c66f..4a5bab065bd 100644
--- a/arch/arm/src/armv7-m/mpu.h
+++ b/arch/arm/src/armv7-m/mpu.h
@@ -170,11 +170,11 @@ unsigned int mpu_allocregion(void);
  *   Determine the smallest value of l2size (log base 2 size) such that the
  *   following is true:
  *
- *   (base & ((1 << l2size) - 1)) + size <= (1 << l2size)
+ *   size <= (1 << l2size)
  *
  ****************************************************************************/
 
-uint8_t mpu_log2regionceil(uintptr_t base, size_t size);
+uint8_t mpu_log2regionceil(size_t size);
 
 /****************************************************************************
  * Name: mpu_log2regionfloor
@@ -183,11 +183,11 @@ uint8_t mpu_log2regionceil(uintptr_t base, size_t size);
  *   Determine the largest value of l2size (log base 2 size) such that the
  *   following is true:
  *
- *   (base & ((1 << l2size) - 1)) + size >= (1 << l2size)
+ *   size >= (1 << l2size)
  *
  ****************************************************************************/
 
-uint8_t mpu_log2regionfloor(uintptr_t base, size_t size);
+uint8_t mpu_log2regionfloor(size_t size);
 
 /****************************************************************************
  * Name: mpu_subregion
@@ -286,7 +286,7 @@ static inline void mpu_priv_stronglyordered(uintptr_t base, size_t size)
 
   /* Select the region size and the sub-region map */
 
-  l2size     = mpu_log2regionceil(base, size);
+  l2size     = mpu_log2regionceil(size);
   subregions = mpu_subregion(base, size, l2size);
 
   /* The configure the region */
@@ -327,7 +327,7 @@ static inline void mpu_user_flash(uintptr_t base, size_t size)
 
   /* Select the region size and the sub-region map */
 
-  l2size     = mpu_log2regionceil(base, size);
+  l2size     = mpu_log2regionceil(size);
   subregions = mpu_subregion(base, size, l2size);
 
   /* The configure the region */
@@ -365,7 +365,7 @@ static inline void mpu_priv_flash(uintptr_t base, size_t size)
 
   /* Select the region size and the sub-region map */
 
-  l2size     = mpu_log2regionceil(base, size);
+  l2size     = mpu_log2regionceil(size);
   subregions = mpu_subregion(base, size, l2size);
 
   /* The configure the region */
@@ -403,7 +403,7 @@ static inline void mpu_user_intsram(uintptr_t base, size_t size)
 
   /* Select the region size and the sub-region map */
 
-  l2size     = mpu_log2regionceil(base, size);
+  l2size     = mpu_log2regionceil(size);
   subregions = mpu_subregion(base, size, l2size);
 
   /* The configure the region */
@@ -442,7 +442,7 @@ static inline void mpu_priv_intsram(uintptr_t base, size_t size)
 
   /* Select the region size and the sub-region map */
 
-  l2size     = mpu_log2regionceil(base, size);
+  l2size     = mpu_log2regionceil(size);
   subregions = mpu_subregion(base, size, l2size);
 
   /* The configure the region */
@@ -481,7 +481,7 @@ static inline void mpu_user_extsram(uintptr_t base, size_t size)
 
   /* Select the region size and the sub-region map */
 
-  l2size     = mpu_log2regionceil(base, size);
+  l2size     = mpu_log2regionceil(size);
   subregions = mpu_subregion(base, size, l2size);
 
   /* The configure the region */
@@ -521,7 +521,7 @@ static inline void mpu_priv_extsram(uintptr_t base, size_t size)
 
   /* Select the region size and the sub-region map */
 
-  l2size     = mpu_log2regionceil(base, size);
+  l2size     = mpu_log2regionceil(size);
   subregions = mpu_subregion(base, size, l2size);
 
   /* The configure the region */
@@ -561,7 +561,7 @@ static inline void mpu_peripheral(uintptr_t base, size_t size)
 
   /* Select the region size and the sub-region map */
 
-  l2size     = mpu_log2regionceil(base, size);
+  l2size     = mpu_log2regionceil(size);
   subregions = mpu_subregion(base, size, l2size);
 
   /* Then configure the region */
diff --git a/arch/arm/src/armv7-m/up_mpu.c b/arch/arm/src/armv7-m/up_mpu.c
index 9370f2108d2..3e802fddfdb 100644
--- a/arch/arm/src/armv7-m/up_mpu.c
+++ b/arch/arm/src/armv7-m/up_mpu.c
@@ -221,24 +221,17 @@ unsigned int mpu_allocregion(void)
  *   Determine the smallest value of l2size (log base 2 size) such that the
  *   following is true:
  *
- *   (base & ((1 << l2size) - 1)) + size <= (1 << l2size)
+ *   size <= (1 << l2size)
  *
  ****************************************************************************/
 
-uint8_t mpu_log2regionceil(uintptr_t base, size_t size)
+uint8_t mpu_log2regionceil(size_t size)
 {
   uint8_t l2size;
 
   /* The minimum permitted region size is 32 bytes (log2(32) = 5. */
 
-  for (l2size = 5; l2size < 32; l2size++)
-    {
-      if ((base & ((1 << l2size) - 1)) + size <= (1 << l2size))
-        {
-          break;
-        }
-    }
-
+  for (l2size = 5; l2size < 32 && size > (1 << l2size); l2size++);
   return l2size;
 }
 
@@ -249,15 +242,15 @@ uint8_t mpu_log2regionceil(uintptr_t base, size_t size)
  *   Determine the largest value of l2size (log base 2 size) such that the
  *   following is true:
  *
- *   (base & ((1 << l2size) - 1)) + size >= (1 << l2size)
+ *   size >= (1 << l2size)
  *
  ****************************************************************************/
 
-uint8_t mpu_log2regionfloor(uintptr_t base, size_t size)
+uint8_t mpu_log2regionfloor(size_t size)
 {
-  uint8_t l2size = mpu_log2regionceil(base, size);
+  uint8_t l2size = mpu_log2regionceil(size);
 
-  if (l2size > 4 && (base & ((1 << l2size) - 1)) + size < (1 << l2size))
+  if (l2size > 4 && size < (1 << l2size))
     {
       l2size--;
     }