diff --git a/lib/chibi/disasm.c b/lib/chibi/disasm.c
index 3a04b3c6..4f9c8493 100644
--- a/lib/chibi/disasm.c
+++ b/lib/chibi/disasm.c
@@ -15,7 +15,7 @@ static void sexp_write_pointer (sexp ctx, void *p, sexp out) {
 }
 
 static sexp disasm (sexp ctx, sexp self, sexp bc, sexp out, int depth) {
-  sexp tmp;
+  sexp tmp=NULL;
   unsigned char *ip, opcode, i;
 
   if (sexp_procedurep(bc)) {
@@ -94,7 +94,7 @@ static sexp disasm (sexp ctx, sexp self, sexp bc, sexp out, int depth) {
   }
   sexp_write_char(ctx, '\n', out);
   if ((opcode == SEXP_OP_PUSH) && (depth < SEXP_DISASM_MAX_DEPTH)
-      && (sexp_bytecodep(tmp) || sexp_procedurep(tmp)))
+      && tmp && (sexp_bytecodep(tmp) || sexp_procedurep(tmp)))
     disasm(ctx, self, tmp, out, depth+1);
   if (ip - sexp_bytecode_data(bc) < sexp_bytecode_length(bc))
     goto loop;
diff --git a/lib/srfi/18/threads.c b/lib/srfi/18/threads.c
index d8f0f865..1473d0e4 100644
--- a/lib/srfi/18/threads.c
+++ b/lib/srfi/18/threads.c
@@ -523,8 +523,10 @@ sexp sexp_scheduler (sexp ctx sexp_api_params(self, n), sexp root_thread) {
     /* either wait on an fd, or just sleep */
     pollfds = sexp_global(res, SEXP_G_THREADS_POLL_FDS);
     if (sexp_portp(sexp_context_event(res)) && sexp_pollfdsp(pollfds)) {
-      if ((k = poll(sexp_pollfds_fds(pollfds), sexp_pollfds_num_fds(pollfds), usecs/1000)) > 0)
+      if ((k = poll(sexp_pollfds_fds(pollfds), sexp_pollfds_num_fds(pollfds), usecs/1000)) > 0) {
+        pfds = sexp_pollfds_fds(pollfds);
         goto unblock_io_threads;
+      }
     } else {
       usleep(usecs);
       sexp_context_waitp(res) = 0;
diff --git a/lib/srfi/95/qsort.c b/lib/srfi/95/qsort.c
index 14329e37..1d115720 100644
--- a/lib/srfi/95/qsort.c
+++ b/lib/srfi/95/qsort.c
@@ -203,6 +203,7 @@ static sexp sexp_sort_x (sexp ctx sexp_api_params(self, n), sexp seq,
       sexp_qsort(ctx, data, 0, len-1);
       if (sexp_opcodep(less) && sexp_opcode_inverse(less))
         sexp_vector_nreverse(ctx, vec);
+      res = vec;
     } else if (! (sexp_procedurep(less) || sexp_opcodep(less))) {
       res = sexp_type_exception(ctx, self, SEXP_PROCEDURE, less);
     } else if (! (sexp_procedurep(key) || sexp_opcodep(key) || sexp_not(key))) {
@@ -212,10 +213,8 @@ static sexp sexp_sort_x (sexp ctx sexp_api_params(self, n), sexp seq,
     }
   }
 
-  if (sexp_pairp(seq))
+  if (sexp_pairp(seq) && ! sexp_exceptionp(res))
     res = sexp_vector_copy_to_list(ctx, vec, seq);
-  else if (! sexp_exceptionp(res))
-    res = vec;
 
   sexp_gc_release1(ctx);
   return res;
diff --git a/main.c b/main.c
index cbdd2bff..6128c538 100644
--- a/main.c
+++ b/main.c
@@ -110,7 +110,7 @@ static sexp sexp_load_standard_repl_env (sexp ctx, sexp env, sexp k) {
 
 void run_main (int argc, char **argv) {
   char *arg, *impmod, *p;
-  sexp env, out=SEXP_FALSE, res=SEXP_VOID, ctx=NULL;
+  sexp out=SEXP_FALSE, res=SEXP_VOID, env=NULL, ctx=NULL;
   sexp_sint_t i, j, len, quit=0, print=0, init_loaded=0;
   sexp_uint_t heap_size=0;
   sexp_gc_var2(tmp, args);
diff --git a/sexp.c b/sexp.c
index e77d6f04..0a662538 100644
--- a/sexp.c
+++ b/sexp.c
@@ -771,7 +771,7 @@ sexp sexp_substring_op (sexp ctx sexp_api_params(self, n), sexp str, sexp start,
 sexp sexp_string_concatenate_op (sexp ctx sexp_api_params(self, n), sexp str_ls, sexp sep) {
   sexp res, ls;
   sexp_uint_t len=0, i=0, sep_len=0;
-  char *p, *csep;
+  char *p, *csep=NULL;
   for (ls=str_ls; sexp_pairp(ls); ls=sexp_cdr(ls), i++)
     if (! sexp_stringp(sexp_car(ls)))
       return sexp_type_exception(ctx, self, SEXP_STRING, sexp_car(ls));