diff --git a/lib/ykpiv.c b/lib/ykpiv.c
index 0a8e830..87a1481 100644
--- a/lib/ykpiv.c
+++ b/lib/ykpiv.c
@@ -103,7 +103,7 @@ ykpiv_rc ykpiv_init(ykpiv_state **state, int verbose) {
   }
   memset(s, 0, sizeof(ykpiv_state));
   s->verbose = verbose;
-  s->context = -1;
+  s->context = SCARD_E_INVALID_HANDLE;
   *state = s;
   return YKPIV_OK;
 }
@@ -120,9 +120,9 @@ ykpiv_rc ykpiv_disconnect(ykpiv_state *state) {
     state->card = 0;
   }
 
-  if(state->context) {
+  if(SCardIsValidContext(state->context) == SCARD_S_SUCCESS) {
     SCardReleaseContext(state->context);
-    state->context = 0;
+    state->context = SCARD_E_INVALID_HANDLE;
   }
 
   return YKPIV_OK;
@@ -205,12 +205,14 @@ ykpiv_rc ykpiv_list_readers(ykpiv_state *state, char *readers, size_t *len) {
   unsigned long num_readers = 0;
   long rc;
 
-  rc = SCardEstablishContext(SCARD_SCOPE_SYSTEM, NULL, NULL, &state->context);
-  if (rc != SCARD_S_SUCCESS) {
-    if(state->verbose) {
-      fprintf (stderr, "error: SCardEstablishContext failed, rc=%08lx\n", rc);
+  if(SCardIsValidContext(state->context) != SCARD_S_SUCCESS) {
+    rc = SCardEstablishContext(SCARD_SCOPE_SYSTEM, NULL, NULL, &state->context);
+    if (rc != SCARD_S_SUCCESS) {
+      if(state->verbose) {
+        fprintf (stderr, "error: SCardEstablishContext failed, rc=%08lx\n", rc);
+      }
+      return YKPIV_PCSC_ERROR;
     }
-    return YKPIV_PCSC_ERROR;
   }
 
   rc = SCardListReaders(state->context, NULL, NULL, &num_readers);