diff --git a/pandas/_libs/src/parser/tokenizer.c b/pandas/_libs/src/parser/tokenizer.c
index c9f7a796a9b1c..61e96fc835e4d 100644
--- a/pandas/_libs/src/parser/tokenizer.c
+++ b/pandas/_libs/src/parser/tokenizer.c
@@ -148,7 +148,7 @@ int parser_init(parser_t *self) {
   self->warn_msg = NULL;
 
   // token stream
-  self->stream = malloc(STREAM_INIT_SIZE * sizeof(char));
+  self->stream = malloc(STREAM_INIT_SIZE);
   if (self->stream == NULL) {
     parser_cleanup(self);
     return PARSER_OUT_OF_MEMORY;
@@ -221,9 +221,8 @@ static int make_stream_space(parser_t *self, size_t nbytes) {
   char *orig_ptr = (void *)self->stream;
   TRACE(("\n\nmake_stream_space: nbytes = %zu.  grow_buffer(self->stream...)\n",
          nbytes))
-  self->stream =
-      (char *)grow_buffer((void *)self->stream, self->stream_len,
-                          &self->stream_cap, nbytes * 2, sizeof(char), &status);
+  self->stream = (char *)grow_buffer((void *)self->stream, self->stream_len,
+                                     &self->stream_cap, nbytes * 2, 1, &status);
   TRACE(("make_stream_space: self->stream=%p, self->stream_len = %zu, "
          "self->stream_cap=%zu, status=%zu\n",
          self->stream, self->stream_len, self->stream_cap, status))
diff --git a/pandas/_libs/src/vendored/ujson/python/objToJSON.c b/pandas/_libs/src/vendored/ujson/python/objToJSON.c
index 5f35860c59cb7..6b957148f94da 100644
--- a/pandas/_libs/src/vendored/ujson/python/objToJSON.c
+++ b/pandas/_libs/src/vendored/ujson/python/objToJSON.c
@@ -984,7 +984,7 @@ static char *List_iterGetName(JSOBJ Py_UNUSED(obj),
 //=============================================================================
 static void Index_iterBegin(JSOBJ Py_UNUSED(obj), JSONTypeContext *tc) {
   GET_TC(tc)->index = 0;
-  GET_TC(tc)->cStr = PyObject_Malloc(20 * sizeof(char));
+  GET_TC(tc)->cStr = PyObject_Malloc(20);
   if (!GET_TC(tc)->cStr) {
     PyErr_NoMemory();
   }
@@ -998,10 +998,10 @@ static int Index_iterNext(JSOBJ obj, JSONTypeContext *tc) {
   const Py_ssize_t index = GET_TC(tc)->index;
   Py_XDECREF(GET_TC(tc)->itemValue);
   if (index == 0) {
-    memcpy(GET_TC(tc)->cStr, "name", sizeof(char) * 5);
+    memcpy(GET_TC(tc)->cStr, "name", 5);
     GET_TC(tc)->itemValue = PyObject_GetAttrString(obj, "name");
   } else if (index == 1) {
-    memcpy(GET_TC(tc)->cStr, "data", sizeof(char) * 5);
+    memcpy(GET_TC(tc)->cStr, "data", 5);
     GET_TC(tc)->itemValue = get_values(obj);
     if (!GET_TC(tc)->itemValue) {
       return 0;
@@ -1033,7 +1033,7 @@ static char *Index_iterGetName(JSOBJ Py_UNUSED(obj), JSONTypeContext *tc,
 static void Series_iterBegin(JSOBJ Py_UNUSED(obj), JSONTypeContext *tc) {
   PyObjectEncoder *enc = (PyObjectEncoder *)tc->encoder;
   GET_TC(tc)->index = 0;
-  GET_TC(tc)->cStr = PyObject_Malloc(20 * sizeof(char));
+  GET_TC(tc)->cStr = PyObject_Malloc(20);
   enc->outputFormat = VALUES; // for contained series
   if (!GET_TC(tc)->cStr) {
     PyErr_NoMemory();
@@ -1048,13 +1048,13 @@ static int Series_iterNext(JSOBJ obj, JSONTypeContext *tc) {
   const Py_ssize_t index = GET_TC(tc)->index;
   Py_XDECREF(GET_TC(tc)->itemValue);
   if (index == 0) {
-    memcpy(GET_TC(tc)->cStr, "name", sizeof(char) * 5);
+    memcpy(GET_TC(tc)->cStr, "name", 5);
     GET_TC(tc)->itemValue = PyObject_GetAttrString(obj, "name");
   } else if (index == 1) {
-    memcpy(GET_TC(tc)->cStr, "index", sizeof(char) * 6);
+    memcpy(GET_TC(tc)->cStr, "index", 6);
     GET_TC(tc)->itemValue = PyObject_GetAttrString(obj, "index");
   } else if (index == 2) {
-    memcpy(GET_TC(tc)->cStr, "data", sizeof(char) * 5);
+    memcpy(GET_TC(tc)->cStr, "data", 5);
     GET_TC(tc)->itemValue = get_values(obj);
     if (!GET_TC(tc)->itemValue) {
       return 0;
@@ -1088,7 +1088,7 @@ static char *Series_iterGetName(JSOBJ Py_UNUSED(obj), JSONTypeContext *tc,
 static void DataFrame_iterBegin(JSOBJ Py_UNUSED(obj), JSONTypeContext *tc) {
   PyObjectEncoder *enc = (PyObjectEncoder *)tc->encoder;
   GET_TC(tc)->index = 0;
-  GET_TC(tc)->cStr = PyObject_Malloc(20 * sizeof(char));
+  GET_TC(tc)->cStr = PyObject_Malloc(20);
   enc->outputFormat = VALUES; // for contained series & index
   if (!GET_TC(tc)->cStr) {
     PyErr_NoMemory();
@@ -1103,13 +1103,13 @@ static int DataFrame_iterNext(JSOBJ obj, JSONTypeContext *tc) {
   const Py_ssize_t index = GET_TC(tc)->index;
   Py_XDECREF(GET_TC(tc)->itemValue);
   if (index == 0) {
-    memcpy(GET_TC(tc)->cStr, "columns", sizeof(char) * 8);
+    memcpy(GET_TC(tc)->cStr, "columns", 8);
     GET_TC(tc)->itemValue = PyObject_GetAttrString(obj, "columns");
   } else if (index == 1) {
-    memcpy(GET_TC(tc)->cStr, "index", sizeof(char) * 6);
+    memcpy(GET_TC(tc)->cStr, "index", 6);
     GET_TC(tc)->itemValue = PyObject_GetAttrString(obj, "index");
   } else if (index == 2) {
-    memcpy(GET_TC(tc)->cStr, "data", sizeof(char) * 5);
+    memcpy(GET_TC(tc)->cStr, "data", 5);
     Py_INCREF(obj);
     GET_TC(tc)->itemValue = obj;
   } else {
diff --git a/pandas/_libs/tslibs/period.pyx b/pandas/_libs/tslibs/period.pyx
index d6d69a49c9539..f697180da5eeb 100644
--- a/pandas/_libs/tslibs/period.pyx
+++ b/pandas/_libs/tslibs/period.pyx
@@ -679,7 +679,7 @@ cdef char* c_strftime(npy_datetimestruct *dts, char *fmt):
     c_date.tm_yday = get_day_of_year(dts.year, dts.month, dts.day) - 1
     c_date.tm_isdst = -1
 
-    result = <char*>malloc(result_len * sizeof(char))
+    result = <char*>malloc(result_len)
     if result is NULL:
         raise MemoryError()