diff --git a/mongoose.c b/mongoose.c
index 1cc814e4..7377d3c3 100644
--- a/mongoose.c
+++ b/mongoose.c
@@ -788,12 +788,13 @@ static void *ff_open(const char *path, int flags) {
   unsigned char mode = FA_READ;
   if (flags & MG_FS_WRITE) mode |= FA_WRITE | FA_OPEN_ALWAYS | FA_OPEN_APPEND;
   if (f_open(&f, path, mode) == 0) {
-    FIL *fp = calloc(1, sizeof(*fp));
-    memcpy(fp, &f, sizeof(*fp));
-    return fp;
-  } else {
-    return NULL;
+    FIL *fp;
+    if ((fp = calloc(1, sizeof(*fp))) != NULL) {
+      memcpy(fp, &f, sizeof(*fp));
+      return fp;
+    }
   }
+  return NULL;
 }
 
 static void ff_close(void *fp) {
@@ -913,9 +914,10 @@ static void *packed_open(const char *path, int flags) {
   struct packed_file *fp = NULL;
   if (data == NULL) return NULL;
   if (flags & MG_FS_WRITE) return NULL;
-  fp = (struct packed_file *) calloc(1, sizeof(*fp));
-  fp->size = size;
-  fp->data = data;
+  if ((fp = (struct packed_file *) calloc(1, sizeof(*fp))) != NULL) {
+    fp->size = size;
+    fp->data = data;
+  }
   return (void *) fp;
 }
 
diff --git a/src/fs_fat.c b/src/fs_fat.c
index 2997dd67..030aafb3 100644
--- a/src/fs_fat.c
+++ b/src/fs_fat.c
@@ -73,12 +73,13 @@ static void *ff_open(const char *path, int flags) {
   unsigned char mode = FA_READ;
   if (flags & MG_FS_WRITE) mode |= FA_WRITE | FA_OPEN_ALWAYS | FA_OPEN_APPEND;
   if (f_open(&f, path, mode) == 0) {
-    FIL *fp = calloc(1, sizeof(*fp));
-    memcpy(fp, &f, sizeof(*fp));
-    return fp;
-  } else {
-    return NULL;
+    FIL *fp;
+    if ((fp = calloc(1, sizeof(*fp))) != NULL) {
+      memcpy(fp, &f, sizeof(*fp));
+      return fp;
+    }
   }
+  return NULL;
 }
 
 static void ff_close(void *fp) {
diff --git a/src/fs_packed.c b/src/fs_packed.c
index 70908193..e2e60a44 100644
--- a/src/fs_packed.c
+++ b/src/fs_packed.c
@@ -67,9 +67,10 @@ static void *packed_open(const char *path, int flags) {
   struct packed_file *fp = NULL;
   if (data == NULL) return NULL;
   if (flags & MG_FS_WRITE) return NULL;
-  fp = (struct packed_file *) calloc(1, sizeof(*fp));
-  fp->size = size;
-  fp->data = data;
+  if ((fp = (struct packed_file *) calloc(1, sizeof(*fp))) != NULL) {
+    fp->size = size;
+    fp->data = data;
+  }
   return (void *) fp;
 }