diff --git a/lib/binutils.c b/lib/binutils.c
index 5f935dc6..102bed10 100644
--- a/lib/binutils.c
+++ b/lib/binutils.c
@@ -34,6 +34,7 @@ int
 chown (char const *file_name, uid_t owner, gid_t group)
 {
   eputs ("chown stub\n");
+  errno = 0;
   return 0;
 }
 
@@ -43,6 +44,7 @@ ctime (int x)
 #if NOISY_TIMES
   eputs ("ctime stub\n");
 #endif
+  errno = 0;
   return 0;
 }
 
@@ -96,6 +98,7 @@ int
 sigsetmask (int x)
 {
   eputs ("sigsetmask stub\n");
+  errno = 0;
   return 0;
 }
 
@@ -151,6 +154,7 @@ int
 sys_siglist (int x)
 {
   eputs ("sys_siglist stub\n");
+  errno = 0;
   return 0;
 }
 
@@ -158,6 +162,7 @@ int
 umask (int x)
 {
   eputs ("umask stub\n");
+  errno = 0;
   return 0;
 }
 
@@ -167,6 +172,7 @@ utime (int x)
 #if NOISY_TIMES
   eputs ("utime stub\n");
 #endif
+  errno = 0;
   return 0;
 }
 
@@ -201,6 +207,7 @@ gmtime (time_t const *time)
 #if NOISY_TIMES
   eputs ("gmtime stub\n");
 #endif
+  errno = 0;
   return localtime (time);
 }
 
diff --git a/lib/gcc.c b/lib/gcc.c
index 9a8dd101..c8eeb9e6 100644
--- a/lib/gcc.c
+++ b/lib/gcc.c
@@ -113,5 +113,6 @@ struct passwd *
 getpwnam (const char *NAME)
 {
   eputs ("getpwnam stub\n");
+  errno = 0;
   return 0;
 }
diff --git a/lib/libc+tcc.c b/lib/libc+tcc.c
index cd51cdde..8355f236 100644
--- a/lib/libc+tcc.c
+++ b/lib/libc+tcc.c
@@ -246,6 +246,7 @@ gettimeofday (struct timeval *tv, struct timezone *tz)
 #if NOISY_TIMES
   eputs ("gettimeofday stub\n");
 #endif
+  errno = 0;
   return 0;
 }
 
@@ -262,6 +263,7 @@ localtime (time_t const *timep)
 #if NOISY_TIMES
   eputs ("localtime stub\n");
 #endif
+  errno = 0;
   return 0;
 }
 
@@ -570,6 +572,7 @@ time (time_t *tloc)
 #if NOISY_TIMES
   eputs ("time stub\n");
 #endif
+  errno = 0;
   return 0;
 }
 
diff --git a/lib/m4.c b/lib/m4.c
index 1e13fe8e..1c9bcfb9 100644
--- a/lib/m4.c
+++ b/lib/m4.c
@@ -66,6 +66,7 @@ int
 fpurge (FILE *stream)
 {
   eputs ("fpurge stub\n");
+  errno = 0;
   return 0;
 }
 
@@ -73,6 +74,7 @@ size_t
 freadahead (FILE *fp)
 {
   eputs ("freadahead stub\n");
+  errno = 0;
   return 0;
 }
 
@@ -130,6 +132,7 @@ int
 pclose (int x)
 {
   eputs ("pclose stub\n");
+  errno = 0;
   return 0;
 }
 
@@ -137,6 +140,7 @@ int
 popen (int x)
 {
   eputs ("popen stub\n");
+  errno = 0;
   return 0;
 }
 
@@ -150,6 +154,7 @@ int
 rewind (int x)
 {
   eputs ("rewind stub\n");
+  errno = 0;
   return 0;
 }
 
@@ -157,6 +162,7 @@ int
 setbuf (int x)
 {
   eputs ("setbuf stub\n");
+  errno = 0;
   return 0;
 }
 
@@ -164,6 +170,7 @@ int
 system (int x)
 {
   eputs ("system stub\n");
+  errno = 0;
   return 0;
 }