diff --git a/Makefile b/Makefile
index 35e9297..4ce178f 100644
--- a/Makefile
+++ b/Makefile
@@ -7,8 +7,8 @@ PREFIX ?= /usr
 
 SRC_COMMON=src/common/
 
-COMMON_SRC = $(SRC_COMMON)main.c $(SRC_COMMON)cpu.c $(SRC_COMMON)udev.c $(SRC_COMMON)pci.c $(SRC_COMMON)printer.c $(SRC_COMMON)args.c $(SRC_COMMON)global.c
-COMMON_HDR = $(SRC_COMMON)ascii.h $(SRC_COMMON)cpu.h $(SRC_COMMON)udev.h $(SRC_COMMON)pci.h $(SRC_COMMON)printer.h $(SRC_COMMON)args.h $(SRC_COMMON)global.h
+COMMON_SRC = $(SRC_COMMON)main.c $(SRC_COMMON)cpu.c $(SRC_COMMON)udev.c $(SRC_COMMON)printer.c $(SRC_COMMON)args.c $(SRC_COMMON)global.c
+COMMON_HDR = $(SRC_COMMON)ascii.h $(SRC_COMMON)cpu.h $(SRC_COMMON)udev.h $(SRC_COMMON)printer.h $(SRC_COMMON)args.h $(SRC_COMMON)global.h
 
 ifneq ($(OS),Windows_NT)
 	GIT_VERSION := "$(shell git describe --abbrev=4 --dirty --always --tags)"
@@ -32,8 +32,8 @@ ifneq ($(OS),Windows_NT)
 		CFLAGS += -DARCH_PPC -std=gnu99 -fstack-protector-all -Wno-language-extension-token
 	else ifeq ($(arch), $(filter $(arch), arm aarch64_be aarch64 arm64 armv8b armv8l armv7l armv6l))
 		SRC_DIR=src/arm/
-		SOURCE += $(COMMON_SRC) $(SRC_DIR)midr.c $(SRC_DIR)uarch.c $(SRC_COMMON)soc.c $(SRC_DIR)soc.c $(SRC_DIR)udev.c
-		HEADERS += $(COMMON_HDR) $(SRC_DIR)midr.h $(SRC_DIR)uarch.h  $(SRC_COMMON)soc.h $(SRC_DIR)soc.h $(SRC_DIR)udev.c $(SRC_DIR)socs.h
+		SOURCE += $(COMMON_SRC) $(SRC_DIR)midr.c $(SRC_DIR)uarch.c $(SRC_COMMON)soc.c $(SRC_DIR)soc.c $(SRC_COMMON)pci.c $(SRC_DIR)udev.c
+		HEADERS += $(COMMON_HDR) $(SRC_DIR)midr.h $(SRC_DIR)uarch.h  $(SRC_COMMON)soc.h $(SRC_DIR)soc.h $(SRC_COMMON)pci.h $(SRC_DIR)udev.c $(SRC_DIR)socs.h
 		CFLAGS += -DARCH_ARM -Wno-unused-parameter -std=c99 -fstack-protector-all
 
 		os := $(shell uname -s)
diff --git a/src/common/pci.c b/src/common/pci.c
index 64b068b..fd46b2f 100644
--- a/src/common/pci.c
+++ b/src/common/pci.c
@@ -1,28 +1,12 @@
 #define _GNU_SOURCE
 
-#include <stdio.h>
-#include <dirent.h>
 #include <sys/stat.h>
-#include <sys/types.h>
-#include <limits.h>
-
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <unistd.h>
-#include <stdio.h>
-#include <stdlib.h>
 #include <dirent.h>
-#include <time.h>
-
-#include <stdbool.h>
 
 #include "udev.h"
 #include "global.h"
 #include "pci.h"
 
-// TODO: Linux only
-// TODO: Only neccesary headers (dont remove limits)
-
 #ifndef PATH_MAX
   #define PATH_MAX 1024
 #endif
@@ -38,51 +22,56 @@
 #define CLASS_VGA_CONTROLLER 0x0300
 #define CLASS_3D_CONTROLLER  0x0302
 
+// Return a list of PCI devices containing only
+// the sysfs path
 struct pci_devices * get_pci_paths(void) {
-  DIR *dfd;
+  DIR *dirp;
 
-  if ((dfd = opendir(PCI_PATH)) == NULL) {
+  if ((dirp = opendir(PCI_PATH)) == NULL) {
     perror("opendir");
-    return false;
+    return NULL;
   }
 
   struct dirent *dp;
-  int numDirs = 0;
+  int numDirs = 0;  
+  errno = 0;
 
-  // TODO: error? readdir
-  while ((dp = readdir(dfd)) != NULL) {
+  while ((dp = readdir(dirp)) != NULL) {
     if (strcmp(dp->d_name, ".") != 0 && strcmp(dp->d_name, "..") != 0)
       numDirs++;
+  }  
+  if (errno != 0) {
+    perror("readdir");
+    return NULL;
   }
 
-  rewinddir(dfd);
+  rewinddir(dirp);
 
-  // char ** pciDirs = emalloc(numDirs * sizeof(char *));
   struct pci_devices * pci = emalloc(sizeof(struct pci_devices));
   pci->num_devices = numDirs;
   pci->devices = emalloc(sizeof(struct pci_device) * pci->num_devices);
-  char * full_path = emalloc(PATH_MAX * sizeof(char *));
+  char * full_path = emalloc(PATH_MAX * sizeof(char));
   struct stat stbuf;
   int i = 0;
 
-  while ((dp = readdir(dfd)) != NULL) {
+  while ((dp = readdir(dirp)) != NULL) {
     if (strcmp(dp->d_name, ".") == 0 || strcmp(dp->d_name, "..") == 0)
       continue;
 
     if (strlen(dp->d_name) > MAX_LENGTH_PCI_DIR_NAME) {
       printErr("Directory name is too long: %s", dp->d_name);
-      return false;
+      return NULL;
     }
 
-    memset(full_path, 0, PATH_MAX * sizeof(char *));
+    memset(full_path, 0, PATH_MAX * sizeof(char));
     snprintf(full_path, min(strlen(PCI_PATH) + strlen(dp->d_name) + 1, PATH_MAX), "%s%s", PCI_PATH, dp->d_name);    
 
-    if (stat(full_path, &stbuf ) == -1) {
+    if (stat(full_path, &stbuf) == -1) {
       perror("stat");
-      return false;
+      return NULL;
     }
 
-    if ((stbuf.st_mode & S_IFMT ) == S_IFDIR) {
+    if ((stbuf.st_mode & S_IFMT) == S_IFDIR) {
       int strLen = min(MAX_LENGTH_PCI_DIR_NAME, strlen(dp->d_name)) + 1;
       pci->devices[i] = emalloc(sizeof(struct pci_device));
       pci->devices[i]->path = ecalloc(sizeof(char), strLen);
@@ -90,17 +79,23 @@ struct pci_devices * get_pci_paths(void) {
       i++;
     }        
   }
+  if (errno != 0) {
+    perror("readdir");
+    return NULL;
+  }
 
   return pci;
 }
 
+// For each PCI device in the list pci, fetch its vendor and 
+// device id using sysfs (e.g., /sys/bus/pci/devices/XXX/{vendor/device})
 void populate_pci_devices(struct pci_devices * pci) {
   int filelen;
   char* buf;
 
   for (int i=0; i < pci->num_devices; i++) {
     struct pci_device* dev = pci->devices[i];
-    int path_size = strlen(PCI_PATH) + strlen(dev->path) + 3;
+    int path_size = strlen(PCI_PATH) + strlen(dev->path) + 2;
 
     // Read vendor_id
     char *vendor_id_path = emalloc(sizeof(char) * (path_size + strlen("vendor")));
@@ -116,7 +111,8 @@ void populate_pci_devices(struct pci_devices * pci) {
 
     // Read device_id
     char *device_id_path = emalloc(sizeof(char) * (path_size + strlen("device")));
-    sprintf(device_id_path, "%s/%s/%s", PCI_PATH, dev->path, "device");    
+    sprintf(device_id_path, "%s/%s/%s", PCI_PATH, dev->path, "device");
+
     if ((buf = read_file(device_id_path, &filelen)) == NULL) {
       printWarn("read_file: %s: %s\n", device_id_path, strerror(errno));
       dev->device_id = 0;
@@ -124,18 +120,28 @@ void populate_pci_devices(struct pci_devices * pci) {
     else {
       dev->device_id = strtol(buf, NULL, 16);
     }
+
+    free(vendor_id_path);
+    free(device_id_path);
   }
 }
 
-// Filter the input in order to get only those PCI devices which 
-// we are interested in (i.e., which vendor is NVIDIA), and return
-// the filtered result.
+// Right now, we are interested in PCI devices which
+// vendor is NVIDIA (to be extended in the future).
+// Should we also restrict to VGA controllers only?
+bool pci_device_is_useful(struct pci_device* dev) {
+  return dev->vendor_id == PCI_VENDOR_NVIDIA;
+}
+
+// Filter the input list in order to get only those PCI devices which 
+// we are interested in (decided by pci_device_is_useful)
+// and return the filtered result.
 struct pci_devices * filter_pci_devices(struct pci_devices * pci) {
   int * devices_to_get = emalloc(sizeof(int) * pci->num_devices);
   int dev_ptr = 0;
 
   for (int i=0; i < pci->num_devices; i++) {
-    if (pci->devices[i]->vendor_id == PCI_VENDOR_NVIDIA) {
+    if (pci_device_is_useful(pci->devices[i])) {
       devices_to_get[dev_ptr] = i;
       dev_ptr++;
     }
@@ -143,27 +149,30 @@ struct pci_devices * filter_pci_devices(struct pci_devices * pci) {
 
   struct pci_devices * pci_filtered = emalloc(sizeof(struct pci_devices));
   pci_filtered->num_devices = dev_ptr;
-  if (pci_filtered->num_devices == 0)
+
+  if (pci_filtered->num_devices == 0) {
     pci_filtered->devices = NULL;
-  else
+  }
+  else {
     pci_filtered->devices = emalloc(sizeof(struct pci_device) * pci_filtered->num_devices);  
 
-  for (int i=0; i < dev_ptr; i++) {
-    pci_filtered->devices[i] = pci->devices[devices_to_get[i]];
+    for (int i=0; i < pci_filtered->num_devices; i++)
+      pci_filtered->devices[i] = pci->devices[devices_to_get[i]];
   }
 
   return pci_filtered;
 }
 
+// Return a list of PCI devices that could be used to infer the SoC.
+// The criteria to determine which devices are suitable for this task
+// is decided in filter_pci_devices.
 struct pci_devices * get_pci_devices(void) {
   struct pci_devices * pci = get_pci_paths();
 
   if (pci == NULL)
-    return false;
+    return NULL;
 
-  populate_pci_devices(pci);
+  populate_pci_devices(pci);  
 
-  struct pci_devices * filtered = filter_pci_devices(pci);  
-
-  return filtered;
+  return filter_pci_devices(pci);
 }
\ No newline at end of file