diff --git a/libguile/gen-scmconfig.c b/libguile/gen-scmconfig.c
index 8d77dfaf2..a3c732039 100644
--- a/libguile/gen-scmconfig.c
+++ b/libguile/gen-scmconfig.c
@@ -1,4 +1,4 @@
-/* Copyright 2003-2013,2018
+/* Copyright 2003-2013,2018,2020
      Free Software Foundation, Inc.
 
    This file is part of Guile.
@@ -20,7 +20,7 @@
 /**********************************************************************
 
   Description of Guile's public config header mechanics:
-  ----------------------------------------------------- 
+  -----------------------------------------------------
 
   Guile has three core headers:
 
@@ -153,7 +153,7 @@ main (int argc, char *argv[])
       "\n"
       "#ifndef SCM_SCMCONFIG_H\n"
       "#define SCM_SCMCONFIG_H\n");
-  
+
   /*** various important headers ***/
   pf ("\n");
   pf ("/* Important headers */\n");
@@ -289,6 +289,12 @@ main (int argc, char *argv[])
   pf ("#define SCM_NEED_BRACES_ON_PTHREAD_MUTEX_INITIALIZER %d /* 0 or 1 */\n",
       SCM_I_GSC_NEED_BRACES_ON_PTHREAD_MUTEX_INITIALIZER);
 
+#ifdef HAVE_PTHREAD_SIGMASK
+  pf ("#define SCM_HAVE_PTHREAD_SIGMASK 1 /* 0 or 1 */\n");
+#else
+  pf ("#define SCM_HAVE_PTHREAD_SIGMASK 0 /* 0 or 1 */\n");
+#endif
+
 #ifdef HAVE_GC_PTHREAD_CANCEL
   pf ("#define SCM_HAVE_GC_PTHREAD_CANCEL 1 /* 0 or 1 */\n");
 #else
diff --git a/libguile/null-threads.h b/libguile/null-threads.h
index 88926fa2f..be72346f0 100644
--- a/libguile/null-threads.h
+++ b/libguile/null-threads.h
@@ -1,7 +1,7 @@
 #ifndef SCM_NULL_THREADS_H
 #define SCM_NULL_THREADS_H
 
-/* Copyright 2005-2006,2010,2018
+/* Copyright 2005-2006,2010,2018,2020
      Free Software Foundation, Inc.
 
    This file is part of Guile.
@@ -83,11 +83,13 @@ scm_i_sched_yield (void)
 
 /* Signals
  */
+#if SCM_HAVE_PTHREAD_SIGMASK == 1
 static inline int
 scm_i_pthread_sigmask (int how, const sigset_t *set, sigset_t *oldset)
 {
   return sigprocmask (how, set, oldset);
 }
+#endif
 
 /* Mutexes
  */