diff --git a/esl_bitfield.c b/esl_bitfield.c
index fbad3ad5..2375c5b5 100644
--- a/esl_bitfield.c
+++ b/esl_bitfield.c
@@ -69,8 +69,10 @@ esl_bitfield_Count(const ESL_BITFIELD *b)
 void
 esl_bitfield_Destroy(ESL_BITFIELD *b)
 {
-  if (b) free(b->b);
-  free(b);
+  if (b) { 
+    free(b->b);
+    free(b);
+  }
 }
 
 
diff --git a/esl_huffman.c b/esl_huffman.c
index 57b4fc21..680ba0a2 100644
--- a/esl_huffman.c
+++ b/esl_huffman.c
@@ -157,12 +157,12 @@ void
 esl_huffman_Destroy(ESL_HUFFMAN *hc)
 {
   if (hc) {
-    free(hc->len);
-    free(hc->code);
-    free(hc->sorted_at);
-    free(hc->dt_len);
-    free(hc->dt_lcode);
-    free(hc->dt_rank);
+    if(hc->len)       free(hc->len);
+    if(hc->code)      free(hc->code);
+    if(hc->sorted_at) free(hc->sorted_at);
+    if(hc->dt_len)    free(hc->dt_len);
+    if(hc->dt_lcode)  free(hc->dt_lcode);
+    if(hc->dt_rank)   free(hc->dt_rank);
     free(hc);
   }
 }
diff --git a/esl_json.c b/esl_json.c
index 66f045ca..a0ad52b6 100644
--- a/esl_json.c
+++ b/esl_json.c
@@ -482,7 +482,7 @@ esl_json_Destroy(ESL_JSON *pi)
 {
   if (pi)
     {
-      free(pi->tok);
+      if(pi->tok) free(pi->tok);
       free(pi);
     }
 }
diff --git a/esl_minimizer.c b/esl_minimizer.c
index 6fa37864..d577fb00 100644
--- a/esl_minimizer.c
+++ b/esl_minimizer.c
@@ -297,7 +297,7 @@ esl_min_cfg_Destroy(ESL_MIN_CFG *cfg)
 {
   if (cfg)
     {
-      free(cfg->u);
+      if(cfg->u) free(cfg->u);
       free(cfg);
     }
 }
diff --git a/esl_mixdchlet.c b/esl_mixdchlet.c
index 0101d244..fa4f12eb 100644
--- a/esl_mixdchlet.c
+++ b/esl_mixdchlet.c
@@ -81,9 +81,9 @@ esl_mixdchlet_Destroy(ESL_MIXDCHLET *dchl)
 {
   if (dchl)
     {
-      free(dchl->q);
+      if(dchl->q)     free(dchl->q);
       esl_mat_DDestroy(dchl->alpha);
-      free(dchl->postq);
+      if(dchl->postq) free(dchl->postq);
       free(dchl);
     }
 }
diff --git a/esl_msaweight.c b/esl_msaweight.c
index 7b5d6d74..84ea4143 100644
--- a/esl_msaweight.c
+++ b/esl_msaweight.c
@@ -569,7 +569,7 @@ esl_msaweight_cfg_Create(void)
 void
 esl_msaweight_cfg_Destroy(ESL_MSAWEIGHT_CFG *cfg)
 {
-  free(cfg);
+  if(cfg) free(cfg);
 }
 
 
diff --git a/esl_rand64.c b/esl_rand64.c
index f7fcd217..3badf05a 100644
--- a/esl_rand64.c
+++ b/esl_rand64.c
@@ -145,7 +145,7 @@ esl_rand64_GetSeed(ESL_RAND64 *rng)
 void
 esl_rand64_Destroy(ESL_RAND64 *rng)
 {
-  free(rng);
+  if(rng) free(rng);
 }
 
 
diff --git a/esl_random.c b/esl_random.c
index e9eecc28..79d0d0cd 100644
--- a/esl_random.c
+++ b/esl_random.c
@@ -249,7 +249,7 @@ esl_randomness_GetSeed(const ESL_RANDOMNESS *r)
 void
 esl_randomness_Destroy(ESL_RANDOMNESS *r)
 {
-  free(r);
+  if(r) free(r);
   return;
 }
 
diff --git a/esl_red_black.c b/esl_red_black.c
index 56dbfe3f..5dbd5f2e 100644
--- a/esl_red_black.c
+++ b/esl_red_black.c
@@ -31,13 +31,15 @@ ESL_RED_BLACK_DOUBLEKEY * esl_red_black_doublekey_Create(){
 }
 
 void esl_red_black_doublekey_Destroy(ESL_RED_BLACK_DOUBLEKEY *tree){
-  if(tree->large != NULL){
-    esl_red_black_doublekey_Destroy(tree->large);
-  }
-  if(tree->small != NULL){
-    esl_red_black_doublekey_Destroy(tree->small);
+  if(tree) { 
+    if(tree->large != NULL){
+      esl_red_black_doublekey_Destroy(tree->large);
+    }
+    if(tree->small != NULL){
+      esl_red_black_doublekey_Destroy(tree->small);
+    }
+    free(tree);
   }
-  free(tree);
 }
 
 void esl_red_black_doublekey_linked_list_Destroy(ESL_RED_BLACK_DOUBLEKEY *tree){
diff --git a/esl_regexp.c b/esl_regexp.c
index 3556e3c4..99e4b0a1 100644
--- a/esl_regexp.c
+++ b/esl_regexp.c
@@ -111,8 +111,10 @@ void
 esl_regexp_Destroy(ESL_REGEXP *machine)
 {
   /* Spencer's clever alloc for the NDFA allows us to free it w/ free()  */
-  if (machine->ndfa != NULL) free(machine->ndfa); 
-  free(machine);
+  if(machine) { 
+    if (machine->ndfa != NULL) free(machine->ndfa); 
+    free(machine);
+  }
   return;
 }