diff --git a/mos-platform/common/c/CMakeLists.txt b/mos-platform/common/c/CMakeLists.txt
index 21cef3a5b..645b04445 100644
--- a/mos-platform/common/c/CMakeLists.txt
+++ b/mos-platform/common/c/CMakeLists.txt
@@ -3,6 +3,9 @@ add_platform_library(common-c
   # ctype.h
   ctype.c
 
+  # errno.h
+  errno.c
+
   # setjmp.h
   setjmp.S
 
@@ -12,11 +15,13 @@ add_platform_library(common-c
 
   # stdlib.h
   abs.cc
+  div.cc
   stdlib.cc
   new.cc
 
   # string.h
   mem.c
+  strerror.c
   string.c
 
   # exception
diff --git a/mos-platform/common/c/ctype.c b/mos-platform/common/c/ctype.c
index 9b25439f8..d1e92262e 100644
--- a/mos-platform/common/c/ctype.c
+++ b/mos-platform/common/c/ctype.c
@@ -1,8 +1,23 @@
 #include <ctype.h>
 
-int isprint(int c) {
+int isalnum(int c) {
+  return isalpha(c) || isdigit(c);
+}
+
+int isalpha(int c) {
+  char ch = (char)c;
+  return ((ch >= 'A') && (ch <= 'Z'))
+    || ((ch >= 'a') && (ch <= 'z'));
+}
+
+int isblank(int c) {
   char ch = (char)c;
-  return ch >= 0x1f && ch < 0x7f /*DEL*/;
+  return ch == ' ' || ch == '\t';
+}
+
+int iscntrl(int c) {
+  char ch = (char)c;
+  return ch < ' ';
 }
 
 int isdigit(int c) {
@@ -10,21 +25,23 @@ int isdigit(int c) {
   return ch >= '0' && ch <= '9';
 }
 
-int isalpha(int c) {
+int isgraph(int c) {
   char ch = (char)c;
-  return ((ch >= 'A') && (ch <= 'Z'))
-    || ((ch >= 'a') && (ch <= 'z'));
+  return isprint(c) && (c != ' ');
 }
 
-int toupper(int c) {
+int islower(int c) {
   char ch = (char)c;
-  if ((ch >= 'a') && (ch <= 'z'))
-    ch &= ~0x20;
-  return ch;
+  return ch >= 'a' && ch <= 'z';
 }
 
-int isalnum(int c) {
-  return isalpha(c) || isdigit(c);
+int isprint(int c) {
+  char ch = (char)c;
+  return ch > 0x1f && ch < 0x7f /*DEL*/;
+}
+
+int ispunct(int c) {
+  return isprint(c) && !isspace(c) && !isalnum(c);
 }
 
 int isspace(int c) {
@@ -33,3 +50,28 @@ int isspace(int c) {
   	(ch == '\f') || (ch == '\r') || (ch == '\v');
 }
 
+int isupper(int c) {
+  char ch = (char)c;
+  return ch >= 'A' && ch <= 'Z';
+}
+
+int isxdigit(int c) {
+  char ch = (char)c;
+  return ((ch >= '0') && (ch <= '9'))
+    || ((ch >= 'a') && (ch <= 'f'))
+    || ((ch >= 'A') && (ch <= 'F'));
+}
+
+int tolower(int c) {
+  char ch = (char)c;
+  if ((ch >= 'A') && (ch <= 'Z'))
+    ch |= 0x20;
+  return ch;
+}
+
+int toupper(int c) {
+  char ch = (char)c;
+  if ((ch >= 'a') && (ch <= 'z'))
+    ch &= ~0x20;
+  return ch;
+}
diff --git a/mos-platform/common/c/div.cc b/mos-platform/common/c/div.cc
new file mode 100644
index 000000000..d55e1fd11
--- /dev/null
+++ b/mos-platform/common/c/div.cc
@@ -0,0 +1,14 @@
+#include <stdlib.h>
+
+template <typename T, typename R> static inline R _div(T numer, T denom) {
+  R result;
+  result.quot = numer / denom;
+  result.rem = numer % denom;
+  return result;
+}
+
+extern "C" {
+div_t div(int numer, int denom) { return _div<int, div_t>(numer, denom); }
+ldiv_t ldiv(long numer, long denom) { return _div<long, ldiv_t>(numer, denom); }
+lldiv_t lldiv(long long numer, long long denom) { return _div<long long, lldiv_t>(numer, denom); }
+}
diff --git a/mos-platform/common/c/errno.c b/mos-platform/common/c/errno.c
new file mode 100644
index 000000000..acfee44d8
--- /dev/null
+++ b/mos-platform/common/c/errno.c
@@ -0,0 +1 @@
+int _errno = 0;
diff --git a/mos-platform/common/c/strerror.c b/mos-platform/common/c/strerror.c
new file mode 100644
index 000000000..5367adaaf
--- /dev/null
+++ b/mos-platform/common/c/strerror.c
@@ -0,0 +1,17 @@
+#include <string.h>
+
+static const char *errors[] = {
+  "ERANGE",
+  "EDOM",
+  "EILSEQ",
+  "EINVAL",
+  "ENOMEM"
+};
+
+__attribute__((weak)) const char *strerror(int n) {
+  if (n > 0) {
+    return errors[((unsigned char) n) - 1];
+  } else {
+    return "";
+  }
+}
diff --git a/mos-platform/common/include/ctype.h b/mos-platform/common/include/ctype.h
index 859d19730..eacaffbe5 100644
--- a/mos-platform/common/include/ctype.h
+++ b/mos-platform/common/include/ctype.h
@@ -1,16 +1,24 @@
-#ifndef _CYTPE_H_
-#define _CYTPE_H_
+#ifndef _CTYPE_H_
+#define _CTYPE_H_
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-extern int isprint(int c);
-extern int isdigit(int c);
-extern int isalpha(int c);
-extern int toupper(int c);
-extern int isspace(int c);
-extern int isalnum(int c);
+int isalnum(int c);
+int isalpha(int c);
+int isblank(int c);
+int iscntrl(int c);
+int isdigit(int c);
+int isgraph(int c);
+int islower(int c);
+int isprint(int c);
+int ispunct(int c);
+int isspace(int c);
+int isupper(int c);
+int isxdigit(int c);
+int tolower(int c);
+int toupper(int c);
 
 #ifdef __cplusplus
 }
diff --git a/mos-platform/common/include/errno.h b/mos-platform/common/include/errno.h
new file mode 100644
index 000000000..beec0a0ff
--- /dev/null
+++ b/mos-platform/common/include/errno.h
@@ -0,0 +1,22 @@
+#ifndef _ERRNO_H_
+#define _ERRNO_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+extern int _errno;
+#define errno (_errno)
+
+#define ERANGE 1
+#define EDOM   2
+#define EILSEQ 3
+#define EINVAL 4
+#define ENOMEM 5
+#define ELAST  5
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // not _ERRNO_H_
diff --git a/mos-platform/common/include/math.h b/mos-platform/common/include/math.h
new file mode 100644
index 000000000..20d1f28e0
--- /dev/null
+++ b/mos-platform/common/include/math.h
@@ -0,0 +1,24 @@
+// Stub implementation of math.h.
+
+#ifndef _MATH_H_
+#define _MATH_H_
+
+#include <stddef.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define FP_NORMAL 0
+#define FP_SUBNORMAL 1
+#define FP_ZERO 2
+#define FP_INFINITE 3
+#define FP_NAN 4
+
+#define INFINITY (1.0f / 0.0f)
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // not _MATH_H_
diff --git a/mos-platform/common/include/stdlib.h b/mos-platform/common/include/stdlib.h
index 784b216a3..51cbbdb08 100644
--- a/mos-platform/common/include/stdlib.h
+++ b/mos-platform/common/include/stdlib.h
@@ -25,6 +25,24 @@ int abs(int i);
 long labs(long i);
 long long llabs(long long i);
 
+typedef struct {
+  int quot;
+  int rem;
+} div_t;
+div_t div(int numer, int denom);
+
+typedef struct {
+  long quot;
+  long rem;
+} ldiv_t;
+ldiv_t ldiv(long numer, long denom);
+
+typedef struct {
+  long long quot;
+  long long rem;
+} lldiv_t;
+lldiv_t lldiv(long long numer, long long denom);
+
 /**
 Simple malloc/free implementation.
 
diff --git a/mos-platform/common/include/string.h b/mos-platform/common/include/string.h
index 4efc5e13d..de1b75262 100644
--- a/mos-platform/common/include/string.h
+++ b/mos-platform/common/include/string.h
@@ -20,6 +20,8 @@ int strcmp(const char *s1, const char *s2);
 
 char *strcpy(char * __restrict__ s1, const char * __restrict__ s2);
 
+const char *strerror(int n);
+
 size_t strlen(const char *s);
 int strncmp(const char *s1, const char *s2, size_t n);
 char *strncpy(char * __restrict__ s1, const char * __restrict__ s2, size_t n);
@@ -30,7 +32,6 @@ size_t strspn(const char* string, const char* in);
 char* strpbrk(const char* string, const char* brk);
 char* strtok(char* string, const char* separators);
 
-
 // Version of memset with better arguments for MOS. All non-pointer arguments
 // can fit in registers, and there is no superfluous return value. Compiler
 // intrinsic memset calls use this version, and user code is free to as well.
diff --git a/mos-platform/common/include/time.h b/mos-platform/common/include/time.h
new file mode 100644
index 000000000..f7d5bc7bf
--- /dev/null
+++ b/mos-platform/common/include/time.h
@@ -0,0 +1,18 @@
+// Stub implementation of time.h.
+
+#ifndef _TIME_H_
+#define _TIME_H_
+
+#include <stddef.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef long time_t;
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // not _TIME_H_
diff --git a/mos-platform/common/include/wchar.h b/mos-platform/common/include/wchar.h
new file mode 100644
index 000000000..a3bd5dd81
--- /dev/null
+++ b/mos-platform/common/include/wchar.h
@@ -0,0 +1,21 @@
+// Stub implementation of wchar.h.
+
+#ifndef _WCHAR_H_
+#define _WCHAR_H_
+
+#include <stddef.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef unsigned long mbstate_t;
+typedef unsigned long wint_t;
+
+#define WEOF 0xFFFFFFFFul
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // not _WCHAR_H_