diff --git a/include/arm9/hardware/ndma.h b/include/arm9/hardware/ndma.h
index 42cba51..b9af035 100644
--- a/include/arm9/hardware/ndma.h
+++ b/include/arm9/hardware/ndma.h
@@ -18,9 +18,9 @@
  *   along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include <tgmath.h>
 #include "mem_map.h"
 #include "types.h"
+#include "util.h"
 
 
 #define NDMA_REGS_BASE           (IO_MEM_ARM9_ONLY + 0x2000)
@@ -100,7 +100,7 @@
 
 
 // REG_NDMA_GLOBAL_CNT
-#define NDMA_ROUND_ROBIN(n)    ((u32)log2(n)<<16 | 1u<<31 | 1u) // n = number of CPU cycles
+#define NDMA_ROUND_ROBIN(n)    (intLog2(n)<<16 | 1u<<31 | 1u) // n = number of CPU cycles
 #define NDMA_HIGHEST_PRIO      (1u)
 
 // REG_NDMA_INT_CNT
@@ -117,7 +117,7 @@
 #define NDMA_SRC_UPDATE_FILL   (3u<<13)
 #define NDMA_SRC_ADDR_RELOAD   (1u<<15)
 // The block length is 2^n words (Example: 2^15 = 32768 words = 0x20000 bytes)
-#define NDMA_BURST_WORDS(n)    ((u32)log2(n)<<16)
+#define NDMA_BURST_WORDS(n)    (intLog2(n)<<16)
 #define NDMA_IMMEDIATE_MODE    (16u<<24)
 #define NDMA_TOTAL_CNT_MODE    (0u)
 #define NDMA_REPEATING_MODE    (1u<<29)
diff --git a/include/util.h b/include/util.h
index 33893e6..f47227d 100644
--- a/include/util.h
+++ b/include/util.h
@@ -40,3 +40,9 @@
 u32 getleu32(const void* ptr);
 
 u32 swap32(u32 val);
+
+static inline u32 intLog2(u32 val)
+{
+	// The result is undefined if __builtin_clz() is called with 0.
+	return (val ? 31u - __builtin_clz(val) : 0u);
+}