diff --git a/src/core/array.c b/src/core/array.c
index 336d0c44..8cccbd44 100644
--- a/src/core/array.c
+++ b/src/core/array.c
@@ -165,7 +165,8 @@ static Janet cfun_array_slice(int32_t argc, Janet *argv) {
     JanetRange range = janet_getslice(argc, argv);
     JanetView view = janet_getindexed(argv, 0);
     JanetArray *array = janet_array(range.end - range.start);
-    memcpy(array->data, view.items + range.start, sizeof(Janet) * (range.end - range.start));
+    if (array->data)
+        memcpy(array->data, view.items + range.start, sizeof(Janet) * (range.end - range.start));
     array->count = range.end - range.start;
     return janet_wrap_array(array);
 }
diff --git a/src/core/asm.c b/src/core/asm.c
index 02eb0f96..fc9b5555 100644
--- a/src/core/asm.c
+++ b/src/core/asm.c
@@ -642,7 +642,7 @@ static JanetAssembleResult janet_asm1(JanetAssembler *parent, Janet source, int
         }
         /* Allocate bytecode array */
         def->bytecode_length = blength;
-        def->bytecode = malloc(sizeof(int32_t) * blength);
+        def->bytecode = malloc(sizeof(uint32_t) * blength);
         if (NULL == def->bytecode) {
             JANET_OUT_OF_MEMORY;
         }
diff --git a/src/core/buffer.c b/src/core/buffer.c
index 1809f512..ddecc67a 100644
--- a/src/core/buffer.c
+++ b/src/core/buffer.c
@@ -172,7 +172,8 @@ static Janet cfun_buffer_new_filled(int32_t argc, Janet *argv) {
         byte = janet_getinteger(argv, 1) & 0xFF;
     }
     JanetBuffer *buffer = janet_buffer(count);
-    memset(buffer->data, byte, count);
+    if (buffer->data)
+        memset(buffer->data, byte, count);
     buffer->count = count;
     return janet_wrap_buffer(buffer);
 }
@@ -236,7 +237,8 @@ static Janet cfun_buffer_slice(int32_t argc, Janet *argv) {
     JanetRange range = janet_getslice(argc, argv);
     JanetByteView view = janet_getbytes(argv, 0);
     JanetBuffer *buffer = janet_buffer(range.end - range.start);
-    memcpy(buffer->data, view.bytes + range.start, range.end - range.start);
+    if (buffer->data)
+        memcpy(buffer->data, view.bytes + range.start, range.end - range.start);
     buffer->count = range.end - range.start;
     return janet_wrap_buffer(buffer);
 }
diff --git a/src/core/debug.c b/src/core/debug.c
index 033fb3e7..80603943 100644
--- a/src/core/debug.c
+++ b/src/core/debug.c
@@ -192,7 +192,7 @@ static Janet cfun_debug_break(int32_t argc, Janet *argv) {
 
 static Janet cfun_debug_unbreak(int32_t argc, Janet *argv) {
     JanetFuncDef *def;
-    int32_t offset;
+    int32_t offset = 0;
     helper_find(argc, argv, &def, &offset);
     janet_debug_unbreak(def, offset);
     return janet_wrap_nil();
@@ -200,7 +200,7 @@ static Janet cfun_debug_unbreak(int32_t argc, Janet *argv) {
 
 static Janet cfun_debug_fbreak(int32_t argc, Janet *argv) {
     JanetFuncDef *def;
-    int32_t offset;
+    int32_t offset = 0;
     helper_find_fun(argc, argv, &def, &offset);
     janet_debug_break(def, offset);
     return janet_wrap_nil();
diff --git a/src/core/gc.c b/src/core/gc.c
index 3d16d16e..88bb538b 100644
--- a/src/core/gc.c
+++ b/src/core/gc.c
@@ -391,9 +391,8 @@ static int janet_gc_idequals(Janet lhs, Janet rhs) {
  * a value and all its children. */
 int janet_gcunroot(Janet root) {
     Janet *vtop = janet_vm_roots + janet_vm_root_count;
-    Janet *v = janet_vm_roots;
     /* Search from top to bottom as access is most likely LIFO */
-    for (v = janet_vm_roots; v < vtop; v++) {
+    for (Janet *v = janet_vm_roots; v < vtop; v++) {
         if (janet_gc_idequals(root, *v)) {
             *v = janet_vm_roots[--janet_vm_root_count];
             return 1;
@@ -405,10 +404,9 @@ int janet_gcunroot(Janet root) {
 /* Remove a root value from the GC. This sets the effective reference count to 0. */
 int janet_gcunrootall(Janet root) {
     Janet *vtop = janet_vm_roots + janet_vm_root_count;
-    Janet *v = janet_vm_roots;
     int ret = 0;
     /* Search from top to bottom as access is most likely LIFO */
-    for (v = janet_vm_roots; v < vtop; v++) {
+    for (Janet *v = janet_vm_roots; v < vtop; v++) {
         if (janet_gc_idequals(root, *v)) {
             *v = janet_vm_roots[--janet_vm_root_count];
             vtop--;
diff --git a/src/core/os.c b/src/core/os.c
index 2e6b0150..f7e50c01 100644
--- a/src/core/os.c
+++ b/src/core/os.c
@@ -125,6 +125,7 @@ static Janet os_execute(int32_t argc, Janet *argv) {
 static Janet os_execute(int32_t argc, Janet *argv) {
     janet_arity(argc, 1, -1);
     const uint8_t **child_argv = malloc(sizeof(uint8_t *) * (argc + 1));
+    int status = 0;
     if (NULL == child_argv) {
         JANET_OUT_OF_MEMORY;
     }
@@ -141,9 +142,10 @@ static Janet os_execute(int32_t argc, Janet *argv) {
         if (-1 == execve((const char *)child_argv[0], (char **)child_argv, NULL)) {
             exit(1);
         }
+    } else {
+        waitpid(pid, &status, 0);
     }
-    int status;
-    waitpid(pid, &status, 0);
+    free(child_argv);
     return janet_wrap_integer(status);
 }
 #endif
diff --git a/src/core/peg.c b/src/core/peg.c
index 61a86755..23611364 100644
--- a/src/core/peg.c
+++ b/src/core/peg.c
@@ -946,9 +946,11 @@ static uint32_t peg_compile1(Builder *b, Janet peg) {
                                         sizeof(peg_specials) / sizeof(SpecialPair),
                                         sizeof(SpecialPair),
                                         sym);
-            if (!sp)
+            if (sp) {
+                sp->special(b, len - 1, tup + 1);
+            } else {
                 peg_panicf(b, "unknown special %S", sym);
-            sp->special(b, len - 1, tup + 1);
+            }
             break;
         }
     }
diff --git a/src/core/string.c b/src/core/string.c
index c2db76a4..94df1417 100644
--- a/src/core/string.c
+++ b/src/core/string.c
@@ -182,8 +182,7 @@ static Janet cfun_string_repeat(int32_t argc, Janet *argv) {
     if (mulres > INT32_MAX) janet_panic("result string is too long");
     uint8_t *newbuf = janet_string_begin((int32_t) mulres);
     uint8_t *end = newbuf + mulres;
-    uint8_t *p = newbuf;
-    for (p = newbuf; p < end; p += view.len) {
+    for (uint8_t *p = newbuf; p < end; p += view.len) {
         memcpy(p, view.bytes, view.len);
     }
     return janet_wrap_string(janet_string_end(newbuf));
diff --git a/src/core/symcache.c b/src/core/symcache.c
index f045a3b6..dff65617 100644
--- a/src/core/symcache.c
+++ b/src/core/symcache.c
@@ -44,7 +44,7 @@ JANET_THREAD_LOCAL uint32_t janet_vm_cache_deleted = 0;
 /* Initialize the cache (allocate cache memory) */
 void janet_symcache_init() {
     janet_vm_cache_capacity = 1024;
-    janet_vm_cache = calloc(1, janet_vm_cache_capacity * sizeof(const uint8_t **));
+    janet_vm_cache = calloc(1, janet_vm_cache_capacity * sizeof(const uint8_t *));
     if (NULL == janet_vm_cache) {
         JANET_OUT_OF_MEMORY;
     }
@@ -121,7 +121,7 @@ notfound:
 static void janet_cache_resize(uint32_t newCapacity) {
     uint32_t i, oldCapacity;
     const uint8_t **oldCache = janet_vm_cache;
-    const uint8_t **newCache = calloc(1, newCapacity * sizeof(const uint8_t **));
+    const uint8_t **newCache = calloc(1, newCapacity * sizeof(const uint8_t *));
     if (newCache == NULL) {
         JANET_OUT_OF_MEMORY;
     }