diff --git a/arch/arm/src/cxd56xx/cxd56_gauge.c b/arch/arm/src/cxd56xx/cxd56_gauge.c
index 8ca302feb02..1decda4d865 100644
--- a/arch/arm/src/cxd56xx/cxd56_gauge.c
+++ b/arch/arm/src/cxd56xx/cxd56_gauge.c
@@ -34,7 +34,6 @@
 #include <stdbool.h>
 #include <errno.h>
 #include <debug.h>
-#include <math.h>
 
 #include <nuttx/kmalloc.h>
 #include <nuttx/power/battery_gauge.h>
diff --git a/arch/arm/src/stm32/stm32_dac.c b/arch/arm/src/stm32/stm32_dac.c
index 5b50b710bd8..7964a06c5d5 100644
--- a/arch/arm/src/stm32/stm32_dac.c
+++ b/arch/arm/src/stm32/stm32_dac.c
@@ -29,7 +29,6 @@
 #include <stdint.h>
 #include <stdbool.h>
 #include <string.h>
-#include <math.h>
 #include <errno.h>
 #include <debug.h>
 
diff --git a/arch/renesas/src/rx65n/rx65n_rspi.c b/arch/renesas/src/rx65n/rx65n_rspi.c
index 95a12f41d20..e91c77f0363 100644
--- a/arch/renesas/src/rx65n/rx65n_rspi.c
+++ b/arch/renesas/src/rx65n/rx65n_rspi.c
@@ -26,7 +26,6 @@
 
 #include <sys/types.h>
 #include <stdint.h>
-#include <math.h>
 #include <stdbool.h>
 #include <semaphore.h>
 #include <errno.h>
@@ -1740,7 +1739,7 @@ static uint32_t rspi_setfrequency(FAR struct spi_dev_s *dev,
   if (frequency != priv->frequency)
     {
       /* Below formula used to calculate bit rate
-       * Bit rate f(PCLK)/(2 × (n + 1) × 2^N) .
+       * Bit rate f(PCLK)/(2 * (n + 1) * 2^N) .
        * n denotes SPBR setting (0,1,2..255) .
        * N denotes a BRDV[1:0] bit setting (0, 1, 2, 3) .
        */
diff --git a/arch/renesas/src/rx65n/rx65n_rspi_sw.c b/arch/renesas/src/rx65n/rx65n_rspi_sw.c
index 074bc163805..b530043dd6e 100644
--- a/arch/renesas/src/rx65n/rx65n_rspi_sw.c
+++ b/arch/renesas/src/rx65n/rx65n_rspi_sw.c
@@ -26,7 +26,6 @@
 
 #include <sys/types.h>
 #include <stdint.h>
-#include <math.h>
 #include <stdbool.h>
 #include <semaphore.h>
 #include <errno.h>
@@ -1375,7 +1374,7 @@ static uint32_t rspi_setfrequency(FAR struct spi_dev_s *dev,
   if (frequency != priv->frequency)
     {
       /* Below formula used to calculate bit rate
-       * Bit rate f(PCLK)/(2 × (n + 1) × 2^N) .
+       * Bit rate f(PCLK)/(2 * (n + 1) * 2^N) .
        * n denotes SPBR setting (0,1,2..255) .
        * N denotes a BRDV[1:0] bit setting (0, 1, 2, 3) .
        */
diff --git a/drivers/audio/cs4344.c b/drivers/audio/cs4344.c
index a44466a49ed..520ab672bd6 100644
--- a/drivers/audio/cs4344.c
+++ b/drivers/audio/cs4344.c
@@ -46,7 +46,6 @@
 #include <nuttx/audio/i2s.h>
 #include <nuttx/audio/audio.h>
 #include <nuttx/audio/cs4344.h>
-#include <nuttx/lib/math.h>
 
 #include "cs4344.h"
 
diff --git a/drivers/audio/cs43l22.c b/drivers/audio/cs43l22.c
index 4a99bcb480b..56eb160b09a 100644
--- a/drivers/audio/cs43l22.c
+++ b/drivers/audio/cs43l22.c
@@ -43,7 +43,6 @@
 #include <sys/types.h>
 #include <sys/ioctl.h>
 
-#include <math.h>
 #include <inttypes.h>
 #include <stdint.h>
 #include <stdio.h>
diff --git a/drivers/audio/cxd56_src.c b/drivers/audio/cxd56_src.c
index 8f1e8d560fb..f21e177326a 100644
--- a/drivers/audio/cxd56_src.c
+++ b/drivers/audio/cxd56_src.c
@@ -24,7 +24,6 @@
 
 #include <errno.h>
 #include <fcntl.h>
-#include <math.h>
 #include <queue.h>
 #include <stdio.h>
 #include <string.h>
diff --git a/drivers/audio/vs1053.c b/drivers/audio/vs1053.c
index 5e1144190c2..d40ad86c85e 100644
--- a/drivers/audio/vs1053.c
+++ b/drivers/audio/vs1053.c
@@ -27,7 +27,6 @@
 #include <sys/types.h>
 #include <sys/ioctl.h>
 
-#include <math.h>
 #include <inttypes.h>
 #include <stdint.h>
 #include <stdbool.h>
diff --git a/drivers/audio/wm8904.c b/drivers/audio/wm8904.c
index 207b3131eb8..a0bab6404af 100644
--- a/drivers/audio/wm8904.c
+++ b/drivers/audio/wm8904.c
@@ -32,7 +32,6 @@
 #include <sys/types.h>
 #include <sys/ioctl.h>
 
-#include <math.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <inttypes.h>
diff --git a/drivers/audio/wm8994.c b/drivers/audio/wm8994.c
index cf2d62cf5dc..839d639d597 100644
--- a/drivers/audio/wm8994.c
+++ b/drivers/audio/wm8994.c
@@ -48,7 +48,6 @@
 #include <nuttx/audio/i2s.h>
 #include <nuttx/audio/audio.h>
 #include <nuttx/audio/wm8994.h>
-#include <nuttx/lib/math.h>
 
 #include "wm8994.h"
 
diff --git a/drivers/wireless/spirit/include/spirit_radio.h b/drivers/wireless/spirit/include/spirit_radio.h
index 20475b62889..f973cb0715f 100644
--- a/drivers/wireless/spirit/include/spirit_radio.h
+++ b/drivers/wireless/spirit/include/spirit_radio.h
@@ -68,7 +68,6 @@
  ******************************************************************************/
 
 #include <stdint.h>
-#include <math.h>
 
 #include "spirit_types.h"
 
diff --git a/libs/libc/stdio/lib_dtoa_engine.c b/libs/libc/stdio/lib_dtoa_engine.c
index 9a4edeb7187..ab6495d19e2 100644
--- a/libs/libc/stdio/lib_dtoa_engine.c
+++ b/libs/libc/stdio/lib_dtoa_engine.c
@@ -37,6 +37,8 @@
  * Included Files
  ****************************************************************************/
 
+#include <math.h>
+
 #include "lib_dtoa_engine.h"
 
 /****************************************************************************
diff --git a/libs/libc/stdio/lib_dtoa_engine.h b/libs/libc/stdio/lib_dtoa_engine.h
index 5444c709ddc..a60e9398759 100644
--- a/libs/libc/stdio/lib_dtoa_engine.h
+++ b/libs/libc/stdio/lib_dtoa_engine.h
@@ -40,7 +40,6 @@
  * Included Files
  ****************************************************************************/
 
-#include <math.h>
 #include <stdint.h>
 #include <float.h>
 
diff --git a/libs/libc/stdio/lib_libvscanf.c b/libs/libc/stdio/lib_libvscanf.c
index 12283705d16..7f6652fd3c7 100644
--- a/libs/libc/stdio/lib_libvscanf.c
+++ b/libs/libc/stdio/lib_libvscanf.c
@@ -24,7 +24,6 @@
 
 #include <nuttx/compiler.h>
 
-#include <math.h>
 #include <stdarg.h>
 #include <stdlib.h>
 #include <stdbool.h>
diff --git a/libs/libc/stdlib/lib_srand.c b/libs/libc/stdlib/lib_srand.c
index e81de14d679..03f181a7197 100644
--- a/libs/libc/stdlib/lib_srand.c
+++ b/libs/libc/stdlib/lib_srand.c
@@ -24,7 +24,6 @@
 
 #include <nuttx/config.h>
 
-#include <math.h>
 #include <stdlib.h>
 
 #include <nuttx/lib/lib.h>
@@ -44,6 +43,12 @@
 #  define CONFIG_LIB_RAND_ORDER 3
 #endif
 
+#ifndef CONFIG_HAVE_DOUBLE
+typedef float        float_t;
+#else
+typedef double       float_t;
+#endif
+
 /* Values needed by the random number generator */
 
 #define RND1_CONSTK  470001
@@ -64,7 +69,7 @@
 
 static inline unsigned long fgenerate1(void);
 #if (CONFIG_LIB_RAND_ORDER == 1)
-static double_t frand1(void);
+static float_t frand1(void);
 #endif
 
 /* Second order congruential generators */
@@ -72,14 +77,14 @@ static double_t frand1(void);
 #if (CONFIG_LIB_RAND_ORDER > 1)
 static inline unsigned long fgenerate2(void);
 #if (CONFIG_LIB_RAND_ORDER == 2)
-static double_t frand2(void);
+static float_t frand2(void);
 #endif
 
 /* Third order congruential generators */
 
 #if (CONFIG_LIB_RAND_ORDER > 2)
 static inline unsigned long fgenerate3(void);
-static double_t frand3(void);
+static float_t frand3(void);
 #endif
 #endif
 
@@ -116,7 +121,7 @@ static inline unsigned long fgenerate1(void)
 }
 
 #if (CONFIG_LIB_RAND_ORDER == 1)
-static double_t frand1(void)
+static float_t frand1(void)
 {
   /* First order congruential generator. */
 
@@ -124,7 +129,7 @@ static double_t frand1(void)
 
   /* Construct an floating point value in the range from 0.0 up to 1.0 */
 
-  return ((double_t)randint) / ((double_t)RND1_CONSTP);
+  return ((float_t)randint) / ((float_t)RND1_CONSTP);
 }
 #endif
 
@@ -156,7 +161,7 @@ static inline unsigned long fgenerate2(void)
 }
 
 #if (CONFIG_LIB_RAND_ORDER == 2)
-static double_t frand2(void)
+static float_t frand2(void)
 {
   /* Second order congruential generator */
 
@@ -164,7 +169,7 @@ static double_t frand2(void)
 
   /* Construct an floating point value in the range from 0.0 up to 1.0 */
 
-  return ((double_t)randint) / ((double_t)RND2_CONSTP);
+  return ((float_t)randint) / ((float_t)RND2_CONSTP);
 }
 #endif
 
@@ -197,7 +202,7 @@ static inline unsigned long fgenerate3(void)
   return randint;
 }
 
-static double_t frand3(void)
+static float_t frand3(void)
 {
   /* Third order congruential generator */
 
@@ -205,7 +210,7 @@ static double_t frand3(void)
 
   /* Construct an floating point value in the range from 0.0 up to 1.0 */
 
-  return ((double_t)randint) / ((double_t)RND3_CONSTP);
+  return ((float_t)randint) / ((float_t)RND3_CONSTP);
 }
 #endif
 #endif
@@ -246,7 +251,7 @@ void srand(unsigned int seed)
 unsigned long nrand(unsigned long limit)
 {
   unsigned long result;
-  double_t ratio;
+  float_t ratio;
 
   /* Loop to be sure a legal random number is generated */
 
@@ -264,7 +269,7 @@ unsigned long nrand(unsigned long limit)
 
       /* Then, produce the return-able value in the requested range */
 
-      result = (unsigned long)(((double_t)limit) * ratio);
+      result = (unsigned long)(((float_t)limit) * ratio);
 
       /* Loop because there is an (unlikely) possibility that rounding
        * could increase the result at the limit value about the limit.