diff --git a/crypto/crypto.c b/crypto/crypto.c
index 9b4391b5bb..401417d874 100644
--- a/crypto/crypto.c
+++ b/crypto/crypto.c
@@ -77,7 +77,7 @@ int up_cryptoinitialize(void)
     }
 #endif
 
-#if CONFIG_CRYPTO_ALGTEST
+#ifdef CONFIG_CRYPTO_ALGTEST
   res = crypto_test();
   if (res)
     {
diff --git a/drivers/mtd/at24xx.c b/drivers/mtd/at24xx.c
index fbb56b7108..32ea3c618e 100644
--- a/drivers/mtd/at24xx.c
+++ b/drivers/mtd/at24xx.c
@@ -356,7 +356,7 @@ static ssize_t at24c_bwrite(FAR struct mtd_dev_s *dev, off_t startblock, size_t
 
   while (blocksleft-- > 0)
     {
-#if AT24XX_ADDRSIZE
+#if AT24XX_ADDRSIZE == 2
       uint16_t offset = startblock * priv->pagesize;
       buf[1] = offset & 0xff;
       buf[0] = (offset >> 8) & 0xff;
diff --git a/drivers/net/dm90x0.c b/drivers/net/dm90x0.c
index 03e1e44f8d..d9f3644a43 100644
--- a/drivers/net/dm90x0.c
+++ b/drivers/net/dm90x0.c
@@ -1411,19 +1411,19 @@ static inline void dm9x_phymode(struct dm9x_driver_s *dm9x)
   uint16_t phyreg0;
   uint16_t phyreg4;
 
-#if CONFIG_DM9X_MODE_AUTO
+#ifdef CONFIG_DM9X_MODE_AUTO
   phyreg0 = 0x1200;  /* Auto-negotiation & Restart Auto-negotiation */
   phyreg4 = 0x01e1;  /* Default flow control disable*/
-#elif CONFIG_DM9X_MODE_10MHD
+#elif defined(CONFIG_DM9X_MODE_10MHD)
   phyreg4 = 0x21;
   phyreg0 = 0x1000;
-#elif CONFIG_DM9X_MODE_10MFD
+#elif defined(CONFIG_DM9X_MODE_10MFD)
   phyreg4 = 0x41;
   phyreg0 = 0x1100;
-#elif CONFIG_DM9X_MODE_100MHD
+#elif defined(CONFIG_DM9X_MODE_100MHD)
   phyreg4 = 0x81;
   phyreg0 = 0x3000;
-#elif CONFIG_DM9X_MODE_100MFD
+#elif defined(CONFIG_DM9X_MODE_100MFD)
   phyreg4 = 0x101;
   phyreg0 = 0x3100;
 #else
diff --git a/drivers/pipes/pipe_common.c b/drivers/pipes/pipe_common.c
index e2f33aceec..c077ea537f 100644
--- a/drivers/pipes/pipe_common.c
+++ b/drivers/pipes/pipe_common.c
@@ -55,7 +55,7 @@
 
 #include <nuttx/kmalloc.h>
 #include <nuttx/fs/fs.h>
-#if CONFIG_DEBUG
+#ifdef CONFIG_DEBUG
 #  include <nuttx/arch.h>
 #endif
 
diff --git a/drivers/serial/serial.c b/drivers/serial/serial.c
index ff4fe55d47..b07f655466 100644
--- a/drivers/serial/serial.c
+++ b/drivers/serial/serial.c
@@ -954,7 +954,7 @@ int uart_poll(FAR struct file *filep, FAR struct pollfd *fds, bool setup)
 
   /* Some sanity checking */
 
-#if CONFIG_DEBUG
+#ifdef CONFIG_DEBUG
   if (!dev || !fds)
     {
       return -ENODEV;
diff --git a/drivers/usbdev/cdcacm.c b/drivers/usbdev/cdcacm.c
index d57eb5aa41..564fbf6229 100644
--- a/drivers/usbdev/cdcacm.c
+++ b/drivers/usbdev/cdcacm.c
@@ -645,7 +645,7 @@ static int cdcacm_setconfig(FAR struct cdcacm_dev_s *priv, uint8_t config)
   int i;
   int ret = 0;
 
-#if CONFIG_DEBUG
+#ifdef CONFIG_DEBUG
   if (priv == NULL)
     {
       usbtrace(TRACE_CLSERROR(USBSER_TRACEERR_INVALIDARG), 0);
@@ -1765,7 +1765,7 @@ static int cdcuart_setup(FAR struct uart_dev_s *dev)
 
   /* Sanity check */
 
-#if CONFIG_DEBUG
+#ifdef CONFIG_DEBUG
   if (!dev || !dev->priv)
     {
       usbtrace(TRACE_CLSERROR(USBSER_TRACEERR_INVALIDARG), 0);
@@ -1806,7 +1806,7 @@ static void cdcuart_shutdown(FAR struct uart_dev_s *dev)
 
   /* Sanity check */
 
-#if CONFIG_DEBUG
+#ifdef CONFIG_DEBUG
   if (!dev || !dev->priv)
     {
        usbtrace(TRACE_CLSERROR(USBSER_TRACEERR_INVALIDARG), 0);
@@ -2065,7 +2065,7 @@ static void cdcuart_rxint(FAR struct uart_dev_s *dev, bool enable)
 
   /* Sanity check */
 
-#if CONFIG_DEBUG
+#ifdef CONFIG_DEBUG
   if (!dev || !dev->priv)
     {
        usbtrace(TRACE_CLSERROR(USBSER_TRACEERR_INVALIDARG), 0);
@@ -2194,7 +2194,7 @@ static void cdcuart_txint(FAR struct uart_dev_s *dev, bool enable)
 
   /* Sanity checks */
 
-#if CONFIG_DEBUG
+#ifdef CONFIG_DEBUG
   if (!dev || !dev->priv)
     {
        usbtrace(TRACE_CLSERROR(USBSER_TRACEERR_INVALIDARG), 0);
@@ -2237,7 +2237,7 @@ static bool cdcuart_txempty(FAR struct uart_dev_s *dev)
 
   usbtrace(CDCACM_CLASSAPI_TXEMPTY, 0);
 
-#if CONFIG_DEBUG
+#ifdef CONFIG_DEBUG
   if (!priv)
     {
       usbtrace(TRACE_CLSERROR(USBSER_TRACEERR_INVALIDARG), 0);
diff --git a/drivers/usbdev/pl2303.c b/drivers/usbdev/pl2303.c
index bb98a717ea..526322cbb4 100644
--- a/drivers/usbdev/pl2303.c
+++ b/drivers/usbdev/pl2303.c
@@ -1046,7 +1046,7 @@ static int usbclass_setconfig(FAR struct pl2303_dev_s *priv, uint8_t config)
   int i;
   int ret = 0;
 
-#if CONFIG_DEBUG
+#ifdef CONFIG_DEBUG
   if (priv == NULL)
     {
       usbtrace(TRACE_CLSERROR(USBSER_TRACEERR_INVALIDARG), 0);
@@ -2016,7 +2016,7 @@ static int usbser_setup(FAR struct uart_dev_s *dev)
 
   /* Sanity check */
 
-#if CONFIG_DEBUG
+#ifdef CONFIG_DEBUG
   if (!dev || !dev->priv)
     {
       usbtrace(TRACE_CLSERROR(USBSER_TRACEERR_INVALIDARG), 0);
@@ -2057,7 +2057,7 @@ static void usbser_shutdown(FAR struct uart_dev_s *dev)
 
   /* Sanity check */
 
-#if CONFIG_DEBUG
+#ifdef CONFIG_DEBUG
   if (!dev || !dev->priv)
     {
        usbtrace(TRACE_CLSERROR(USBSER_TRACEERR_INVALIDARG), 0);
@@ -2119,7 +2119,7 @@ static void usbser_rxint(FAR struct uart_dev_s *dev, bool enable)
 
   /* Sanity check */
 
-#if CONFIG_DEBUG
+#ifdef CONFIG_DEBUG
   if (!dev || !dev->priv)
     {
        usbtrace(TRACE_CLSERROR(USBSER_TRACEERR_INVALIDARG), 0);
@@ -2210,7 +2210,7 @@ static void usbser_txint(FAR struct uart_dev_s *dev, bool enable)
 
   /* Sanity checks */
 
-#if CONFIG_DEBUG
+#ifdef CONFIG_DEBUG
   if (!dev || !dev->priv)
     {
        usbtrace(TRACE_CLSERROR(USBSER_TRACEERR_INVALIDARG), 0);
@@ -2253,7 +2253,7 @@ static bool usbser_txempty(FAR struct uart_dev_s *dev)
 
   usbtrace(PL2303_CLASSAPI_TXEMPTY, 0);
 
-#if CONFIG_DEBUG
+#ifdef CONFIG_DEBUG
   if (!priv)
     {
       usbtrace(TRACE_CLSERROR(USBSER_TRACEERR_INVALIDARG), 0);
diff --git a/drivers/usbdev/usbmsc.c b/drivers/usbdev/usbmsc.c
index 941563494c..6a6d425b04 100644
--- a/drivers/usbdev/usbmsc.c
+++ b/drivers/usbdev/usbmsc.c
@@ -934,7 +934,7 @@ int usbmsc_setconfig(FAR struct usbmsc_dev_s *priv, uint8_t config)
   int i;
   int ret = 0;
 
-#if CONFIG_DEBUG
+#ifdef CONFIG_DEBUG
   if (priv == NULL)
     {
       usbtrace(TRACE_CLSERROR(USBMSC_TRACEERR_SETCONFIGINVALIDARGS), 0);
diff --git a/drivers/video/ov2640.c b/drivers/video/ov2640.c
index 7256fbc202..1e736f5e07 100644
--- a/drivers/video/ov2640.c
+++ b/drivers/video/ov2640.c
@@ -811,7 +811,7 @@ static int ovr2640_chipid(FAR struct i2c_dev_s *i2c)
 {
   uint8_t pidl;
   uint8_t pidh;
-#if CONFIG_DEBUG_GRAPHICS
+#ifdef CONFIG_DEBUG_GRAPHICS
   uint8_t midh;
   uint8_t midl;
 #endif
@@ -829,7 +829,7 @@ static int ovr2640_chipid(FAR struct i2c_dev_s *i2c)
   pidl = ov2640_getreg(i2c, 0x0a);      /* Product ID (MS) */
   pidh = ov2640_getreg(i2c, 0x0b);      /* Product ID (LS) */
 
-#if CONFIG_DEBUG_GRAPHICS
+#ifdef CONFIG_DEBUG_GRAPHICS
   midh = ov2640_getreg(i2c, 0x1c); /* Manufacturer ID (high) = 0x7f */
   midl = ov2640_getreg(i2c, 0x1d); /* Manufacturer ID (low) = 0xa2 */
 #endif
diff --git a/graphics/nxbe/nxbe_colormap.c b/graphics/nxbe/nxbe_colormap.c
index 536c317541..d5d84e238c 100644
--- a/graphics/nxbe/nxbe_colormap.c
+++ b/graphics/nxbe/nxbe_colormap.c
@@ -81,7 +81,7 @@
  *
  ****************************************************************************/
 
-#if CONFIG_FB_CMAP
+#ifdef CONFIG_FB_CMAP
 int nxbe_colormap(FAR NX_DRIVERTYPE *dev)
 {
   struct fb_cmap_s cmap;
diff --git a/graphics/nxmu/nxmu_server.c b/graphics/nxmu/nxmu_server.c
index eb7fbd75ca..1f13dba908 100644
--- a/graphics/nxmu/nxmu_server.c
+++ b/graphics/nxmu/nxmu_server.c
@@ -192,7 +192,7 @@ static inline int nxmu_setup(FAR const char *mqname, FAR NX_DRIVERTYPE *dev,
       return ERROR;
     }
 
-#if CONFIG_FB_CMAP
+#ifdef CONFIG_FB_CMAP
   ret = nxbe_colormap(dev);
   if (ret < 0)
     {
diff --git a/graphics/nxsu/nx_open.c b/graphics/nxsu/nx_open.c
index 5132b36e96..3f4629f90c 100644
--- a/graphics/nxsu/nx_open.c
+++ b/graphics/nxsu/nx_open.c
@@ -125,7 +125,7 @@ static inline int nxsu_setup(FAR NX_DRIVERTYPE *dev,
       return ERROR;
     }
 
-#if CONFIG_FB_CMAP
+#ifdef CONFIG_FB_CMAP
   ret = nxbe_colormap(dev);
   if (ret < 0)
     {
diff --git a/include/cxx/cmath b/include/cxx/cmath
index b30d5548b7..998406c153 100644
--- a/include/cxx/cmath
+++ b/include/cxx/cmath
@@ -51,7 +51,7 @@
 
 namespace std
 {
-#if CONFIG_HAVE_FLOAT
+#ifdef CONFIG_HAVE_FLOAT
   using ::acosf;
   using ::asinf;
   using ::atanf;
@@ -78,7 +78,7 @@ namespace std
   using ::tanhf;
 #endif
 
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
   using ::acos;
   using ::asin;
   using ::atan;
diff --git a/include/nuttx/float.h b/include/nuttx/float.h
index a8e4aa28b5..a4d8945ee5 100644
--- a/include/nuttx/float.h
+++ b/include/nuttx/float.h
@@ -61,7 +61,7 @@
 
 #define FLT_MANT_DIG 24
 
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 #  define DBL_MANT_DIG 53
 #else
 #  define DBL_MANT_DIG FLT_MANT_DIG
@@ -88,7 +88,7 @@
 
 #define FLT_DIG 6
 
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 #  define DBL_DIG 15  /* 10 */
 #else
 #  define DBL_DIG FLT_DIG
@@ -106,7 +106,7 @@
 
 #define FLT_MIN_EXP (-125)
 
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 #  define DBL_MIN_EXP (-1021)
 #else
 #  define DBL_MIN_EXP FLT_MIN_EXP
@@ -124,7 +124,7 @@
 
 #define FLT_MIN_10_EXP (-37)
 
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 #  define DBL_MIN_10_EXP (-307)  /* -37 */
 #else
 #  define DBL_MIN_10_EXP FLT_MIN_10_EXP
@@ -142,7 +142,7 @@
 
 #define FLT_MAX_EXP 128
 
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 #  define DBL_MAX_EXP 1024
 #else
 #  define DBL_MAX_EXP FLT_MAX_EXP
@@ -160,7 +160,7 @@
 
 #define FLT_MAX_10_EXP 38  /* 37 */
 
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 #  define DBL_MAX_10_EXP 308  /* 37 */
 #else
 #  define DBL_MAX_10_EXP FLT_MAX_10_EXP
@@ -176,7 +176,7 @@
 
 #define FLT_MAX 3.40282347e+38F  /* 1E+37 */
 
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 #  define DBL_MAX 1.7976931348623157e+308  /* 1E+37 */
 #else
 #  define DBL_MAX FLT_MAX
@@ -194,7 +194,7 @@
 
 #define FLT_EPSILON 1.1920929e-07F  /* 1E-5 */
 
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 #  define DBL_EPSILON 2.2204460492503131e-16  /* 1E-9 */
 #else
 #  define DBL_EPSILON FLT_EPSILON
@@ -210,7 +210,7 @@
 
 #define FLT_MIN 1.17549435e-38F  /* 1E-37 */
 
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 #define DBL_MIN 2.2250738585072014e-308  /* 1E-37 */
 #else
 #  define DBL_MIN FLT_MIN
diff --git a/include/nuttx/math.h b/include/nuttx/math.h
index 40990352af..6ee91eab7e 100644
--- a/include/nuttx/math.h
+++ b/include/nuttx/math.h
@@ -128,7 +128,7 @@ extern "C"
 /* General Functions ********************************************************/
 
 float       ceilf (float x);
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 double      ceil  (double x);
 #endif
 #ifdef CONFIG_HAVE_LONG_DOUBLE
@@ -136,7 +136,7 @@ long double ceill (long double x);
 #endif
 
 float       floorf(float x);
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 double      floor (double x);
 #endif
 #ifdef CONFIG_HAVE_LONG_DOUBLE
@@ -144,7 +144,7 @@ long double floorl(long double x);
 #endif
 
 float       roundf(float x);
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 double      round (double x);
 #endif
 #ifdef CONFIG_HAVE_LONG_DOUBLE
@@ -152,7 +152,7 @@ long double roundl(long double x);
 #endif
 
 float       rintf(float x);      /* Not implemented */
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 double      rint(double x);
 #endif
 #ifdef CONFIG_HAVE_LONG_DOUBLE
@@ -160,7 +160,7 @@ long double rintl(long double x); /* Not implemented */
 #endif
 
 float       fabsf (float x);
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 double      fabs  (double x);
 #endif
 #ifdef CONFIG_HAVE_LONG_DOUBLE
@@ -168,7 +168,7 @@ long double fabsl (long double x);
 #endif
 
 float       modff (float x, float *iptr);
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 double      modf  (double x, double *iptr);
 #endif
 #ifdef CONFIG_HAVE_LONG_DOUBLE
@@ -176,7 +176,7 @@ long double modfl (long double x, long double *iptr);
 #endif
 
 float       fmodf (float x, float div);
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 double      fmod  (double x, double div);
 #endif
 #ifdef CONFIG_HAVE_LONG_DOUBLE
@@ -186,7 +186,7 @@ long double fmodl (long double x, long double div);
 /* Exponential and Logarithmic Functions ************************************/
 
 float       powf  (float b, float e);
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 double      pow   (double b, double e);
 #endif
 #ifdef CONFIG_HAVE_LONG_DOUBLE
@@ -195,7 +195,7 @@ long double powl  (long double b, long double e);
 
 float       expf  (float x);
 #define expm1f(x) (expf(x) - 1.0)
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 double      exp   (double x);
 #define expm1(x) (exp(x) - 1.0)
 #endif
@@ -205,7 +205,7 @@ long double expl  (long double x);
 #endif
 
 float       logf  (float x);
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 double      log   (double x);
 #endif
 #ifdef CONFIG_HAVE_LONG_DOUBLE
@@ -213,7 +213,7 @@ long double logl  (long double x);
 #endif
 
 float       log10f(float x);
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 double      log10 (double x);
 #endif
 #ifdef CONFIG_HAVE_LONG_DOUBLE
@@ -221,7 +221,7 @@ long double log10l(long double x);
 #endif
 
 float       log2f (float x);
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 double      log2  (double x);
 #endif
 #ifdef CONFIG_HAVE_LONG_DOUBLE
@@ -229,7 +229,7 @@ long double log2l (long double x);
 #endif
 
 float       sqrtf (float x);
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 double      sqrt  (double x);
 #endif
 #ifdef CONFIG_HAVE_LONG_DOUBLE
@@ -237,7 +237,7 @@ long double sqrtl (long double x);
 #endif
 
 float       ldexpf(float x, int n);
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 double      ldexp (double x, int n);
 #endif
 #ifdef CONFIG_HAVE_LONG_DOUBLE
@@ -245,7 +245,7 @@ long double ldexpl(long double x, int n);
 #endif
 
 float       frexpf(float x, int *exp);
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 double      frexp (double x, int *exp);
 #endif
 #ifdef CONFIG_HAVE_LONG_DOUBLE
@@ -255,7 +255,7 @@ long double frexpl(long double x, int *exp);
 /* Trigonometric Functions **************************************************/
 
 float       sinf  (float x);
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 double      sin   (double x);
 #endif
 #ifdef CONFIG_HAVE_LONG_DOUBLE
@@ -263,7 +263,7 @@ long double sinl  (long double x);
 #endif
 
 float       cosf  (float x);
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 double      cos   (double x);
 #endif
 #ifdef CONFIG_HAVE_LONG_DOUBLE
@@ -271,7 +271,7 @@ long double cosl  (long double x);
 #endif
 
 float       tanf  (float x);
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 double      tan   (double x);
 #endif
 #ifdef CONFIG_HAVE_LONG_DOUBLE
@@ -279,7 +279,7 @@ long double tanl  (long double x);
 #endif
 
 float       asinf (float x);
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 double      asin  (double x);
 #endif
 #ifdef CONFIG_HAVE_LONG_DOUBLE
@@ -287,7 +287,7 @@ long double asinl (long double x);
 #endif
 
 float       acosf (float x);
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 double      acos  (double x);
 #endif
 #ifdef CONFIG_HAVE_LONG_DOUBLE
@@ -295,7 +295,7 @@ long double acosl (long double x);
 #endif
 
 float       atanf (float x);
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 double      atan  (double x);
 #endif
 #ifdef CONFIG_HAVE_LONG_DOUBLE
@@ -303,7 +303,7 @@ long double atanl (long double x);
 #endif
 
 float       atan2f(float y, float x);
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 double      atan2 (double y, double x);
 #endif
 #ifdef CONFIG_HAVE_LONG_DOUBLE
@@ -311,7 +311,7 @@ long double atan2l(long double y, long double x);
 #endif
 
 float       sinhf (float x);
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 double      sinh  (double x);
 #endif
 #ifdef CONFIG_HAVE_LONG_DOUBLE
@@ -319,7 +319,7 @@ long double sinhl (long double x);
 #endif
 
 float       coshf (float x);
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 double      cosh  (double x);
 #endif
 #ifdef CONFIG_HAVE_LONG_DOUBLE
@@ -327,7 +327,7 @@ long double coshl (long double x);
 #endif
 
 float       tanhf (float x);
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 double      tanh  (double x);
 #endif
 #ifdef CONFIG_HAVE_LONG_DOUBLE
@@ -335,7 +335,7 @@ long double tanhl (long double x);
 #endif
 
 float       asinhf (float x);
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 double      asinh  (double x);
 #endif
 #ifdef CONFIG_HAVE_LONG_DOUBLE
@@ -343,7 +343,7 @@ long double asinhl (long double x);
 #endif
 
 float       acoshf (float x);
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 double      acosh  (double x);
 #endif
 #ifdef CONFIG_HAVE_LONG_DOUBLE
@@ -351,7 +351,7 @@ long double acoshl (long double x);
 #endif
 
 float       atanhf (float x);
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 double      atanh  (double x);
 #endif
 #ifdef CONFIG_HAVE_LONG_DOUBLE
@@ -360,7 +360,7 @@ long double atanhl (long double x);
 
 float       erff (float x);
 #define     erfcf(x) (1 - erff(x))
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 double      erf  (double x);
 #define     erfc(x) (1 - erf(x))
 #endif
@@ -370,7 +370,7 @@ long double erfl (long double x);
 #endif
 
 float       copysignf (float x, float y);
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 double      copysign  (double x, double y);
 #endif
 #ifdef CONFIG_HAVE_LONG_DOUBLE
@@ -378,7 +378,7 @@ long double copysignl (long double x, long double y);
 #endif
 
 float       truncf (float x);
-#if CONFIG_HAVE_DOUBLE
+#ifdef CONFIG_HAVE_DOUBLE
 double      trunc (double x);
 #endif
 #ifdef CONFIG_HAVE_LONG_DOUBLE
diff --git a/include/nuttx/timers/rtc.h b/include/nuttx/timers/rtc.h
index d714e040f1..7cbc928d92 100644
--- a/include/nuttx/timers/rtc.h
+++ b/include/nuttx/timers/rtc.h
@@ -111,7 +111,7 @@
  * RTC upper half driver is built.
  */
 
-#if CONFIG_RTC_DRIVER
+#ifdef CONFIG_RTC_DRIVER
 
 /* IOCTL Commands ***********************************************************/
 /* RTC driver IOCTL commands.  These are Linux compatible command names, not
diff --git a/libc/stdio/lib_fgetpos.c b/libc/stdio/lib_fgetpos.c
index 5727c63ef9..322890613e 100644
--- a/libc/stdio/lib_fgetpos.c
+++ b/libc/stdio/lib_fgetpos.c
@@ -104,7 +104,7 @@ int fgetpos(FAR FILE *stream, FAR fpos_t *pos)
 {
   long position;
 
-#if CONFIG_DEBUG
+#ifdef CONFIG_DEBUG
   if (!stream || !pos)
     {
       set_errno(EINVAL);
diff --git a/libc/stdio/lib_fsetpos.c b/libc/stdio/lib_fsetpos.c
index 6cf1c9eedb..d33fe4ca30 100644
--- a/libc/stdio/lib_fsetpos.c
+++ b/libc/stdio/lib_fsetpos.c
@@ -104,7 +104,7 @@
 
 int fsetpos(FAR FILE *stream, FAR fpos_t *pos)
 {
-#if CONFIG_DEBUG
+#ifdef CONFIG_DEBUG
   if (!stream || !pos)
     {
       set_errno(EINVAL);
diff --git a/libxx/libxx_cxa_atexit.cxx b/libxx/libxx_cxa_atexit.cxx
index d7a82fe5b7..5e01f99f27 100644
--- a/libxx/libxx_cxa_atexit.cxx
+++ b/libxx/libxx_cxa_atexit.cxx
@@ -83,7 +83,7 @@ extern "C"
   //
   //*************************************************************************
 
-#if CONFIG_SCHED_ONEXIT
+#ifdef CONFIG_SCHED_ONEXIT
   static void __cxa_callback(int exitcode, FAR void *arg)
   {
     FAR struct __cxa_atexit_s *alloc = (FAR struct __cxa_atexit_s *)arg;
@@ -118,7 +118,7 @@ extern "C"
 
   int __cxa_atexit(__cxa_exitfunc_t func, FAR void *arg, FAR void *dso_handle)
     {
-#if CONFIG_SCHED_ONEXIT
+#ifdef CONFIG_SCHED_ONEXIT
       // Allocate memory to hold the marshaled __cxa_exitfunc_t call
       // information.
 
diff --git a/net/neighbor/neighbor.h b/net/neighbor/neighbor.h
index 087f1a414c..0a2a1c287f 100644
--- a/net/neighbor/neighbor.h
+++ b/net/neighbor/neighbor.h
@@ -70,7 +70,7 @@
 
 struct neighbor_addr_s
 {
-#if CONFIG_NET_IPv6_NEIGHBOR_ADDRTYPE
+#ifdef CONFIG_NET_IPv6_NEIGHBOR_ADDRTYPE
   CONFIG_NET_IPv6_NEIGHBOR_ADDRTYPE na_addr;
 #else
   struct ether_addr na_addr;
diff --git a/net/socket/net_sockets.c b/net/socket/net_sockets.c
index 6c7e1d1128..83ad061f6e 100644
--- a/net/socket/net_sockets.c
+++ b/net/socket/net_sockets.c
@@ -217,7 +217,7 @@ int sockfd_allocate(int minsd)
 
 void sock_release(FAR struct socket *psock)
 {
-#if CONFIG_DEBUG
+#ifdef CONFIG_DEBUG
   if (psock)
 #endif
     {
diff --git a/sched/group/group_killchildren.c b/sched/group/group_killchildren.c
index a320d50bc5..265b04036b 100644
--- a/sched/group/group_killchildren.c
+++ b/sched/group/group_killchildren.c
@@ -43,7 +43,7 @@
 
 #include "group/group.h"
 
-#if HAVE_GROUP_MEMBERS
+#ifdef HAVE_GROUP_MEMBERS
 
 /****************************************************************************
  * Private Functions
diff --git a/sched/sched/sched_timerexpiration.c b/sched/sched/sched_timerexpiration.c
index 7546ec8046..8c223d4cb0 100644
--- a/sched/sched/sched_timerexpiration.c
+++ b/sched/sched/sched_timerexpiration.c
@@ -317,7 +317,7 @@ static void sched_timer_start(unsigned int ticks)
     {
       struct timespec ts;
 
-#if CONFIG_SCHED_TICKLESS_LIMIT_MAX_SLEEP
+#ifdef CONFIG_SCHED_TICKLESS_LIMIT_MAX_SLEEP
       if (ticks > g_oneshot_maxticks)
         {
           ticks = g_oneshot_maxticks;
diff --git a/sched/task/task_restart.c b/sched/task/task_restart.c
index 0d86326968..a81115c173 100644
--- a/sched/task/task_restart.c
+++ b/sched/task/task_restart.c
@@ -151,7 +151,7 @@ int task_restart(pid_t pid)
 
       /* Kill any children of this thread */
 
-#if HAVE_GROUP_MEMBERS
+#ifdef HAVE_GROUP_MEMBERS
       (void)group_killchildren(tcb);
 #endif