diff --git a/include/cli/directives/lookup.h b/include/cli/directives/lookup.h
index b6fb39b..eccf097 100644
--- a/include/cli/directives/lookup.h
+++ b/include/cli/directives/lookup.h
@@ -30,5 +30,5 @@ typedef struct {
 
 bool             cli_lkup_command(const char *command, cli_drt_desc_t *dst);
 bool             cli_lkup_option(const char *command, cli_drt_desc_t *dst);
-cli_lkup_table_t cli_lkup_cmdtable();
-cli_lkup_table_t cli_lkup_opttable();
+cli_lkup_table_t cli_lkup_cmdtable(void);
+cli_lkup_table_t cli_lkup_opttable(void);
diff --git a/include/cli/output.h b/include/cli/output.h
index 41b1d0d..7c7e554 100644
--- a/include/cli/output.h
+++ b/include/cli/output.h
@@ -24,8 +24,8 @@
 
 #include "os/console.h"
 
-void cli_out_newline();
-void cli_out_reset();
+void cli_out_newline(void);
+void cli_out_reset(void);
 void cli_out_progress(const char *fmt, ...);
 void cli_out_success(const char *fmt, ...);
 void cli_out_error(const char *fmt, ...);
diff --git a/include/os/console.h b/include/os/console.h
index c40eb37..09b7d72 100644
--- a/include/os/console.h
+++ b/include/os/console.h
@@ -36,5 +36,5 @@ typedef enum {
   TM_COLOR_RESET
 } color_t;
 
-csz_t os_console_get_sz();
+csz_t os_console_get_sz(void);
 void  os_console_set_color(color_t color, bool bold);
diff --git a/include/os/fs.h b/include/os/fs.h
index 481d415..9d74eb6 100644
--- a/include/os/fs.h
+++ b/include/os/fs.h
@@ -81,4 +81,4 @@ os_fs_tm_dyrecipe(char **dst, const char *repo_name, const char *pkg_name);
 size_t os_fs_tm_dyplugins(const char **dst);
 size_t os_fs_tm_dyplugin(const char **dst, const char *plugin);
 size_t os_fs_tm_dyplugconf(const char **dst, const char *plugin);
-bool   os_fs_tm_init();
+bool   os_fs_tm_init(void);
diff --git a/include/os/no-optional/console.h b/include/os/no-optional/console.h
index c02e6ae..83ce325 100644
--- a/include/os/no-optional/console.h
+++ b/include/os/no-optional/console.h
@@ -20,5 +20,5 @@
 
 #include "os/console.h"
 
-csz_t noopt_console_get_sz();
+csz_t noopt_console_get_sz(void);
 void  noopt_console_set_color(color_t color, bool bold);
diff --git a/include/os/posix/console.h b/include/os/posix/console.h
index 50ab137..559f130 100644
--- a/include/os/posix/console.h
+++ b/include/os/posix/console.h
@@ -22,5 +22,5 @@
 
 #include "os/console.h"
 
-csz_t posix_console_get_sz();
+csz_t posix_console_get_sz(void);
 void  posix_console_set_color(color_t color, bool bold);
diff --git a/include/os/posix/fs.h b/include/os/posix/fs.h
index f98d4b7..cf95ebd 100644
--- a/include/os/posix/fs.h
+++ b/include/os/posix/fs.h
@@ -48,4 +48,4 @@ size_t posix_fs_tm_dyplugins(const char **dst);
 size_t posix_fs_tm_dyplugin(const char **dst, const char *plugin);
 size_t posix_fs_tm_dyplugconf(const char **dst, const char *plugin);
 size_t posix_fs_tm_dyexecpath(const char **dst, const char *exec);
-bool   posix_fs_tm_init();
+bool   posix_fs_tm_init(void);
diff --git a/include/tm-mem.h b/include/tm-mem.h
index c6953c4..6750888 100644
--- a/include/tm-mem.h
+++ b/include/tm-mem.h
@@ -19,5 +19,5 @@
 #pragma once
 
 void mem_safe_free(const void *ptr);
-void mem_oom();
+void mem_oom(void);
 void mem_chkoom(void *ptr);
diff --git a/src/common/cli/directives/commands/help.c b/src/common/cli/directives/commands/help.c
index 71b9d16..d3744f2 100644
--- a/src/common/cli/directives/commands/help.c
+++ b/src/common/cli/directives/commands/help.c
@@ -29,7 +29,7 @@
 #define OPT_SEPARATOR_LEN    2
 #define COLUMN_SEPARATOR_LEN 4
 
-static void print_indent() {
+static void print_indent(void) {
   cli_out_space(BASE_LINE_LEN);
 }
 
diff --git a/src/common/cli/directives/commands/list.c b/src/common/cli/directives/commands/list.c
index 3180aa4..50e9749 100644
--- a/src/common/cli/directives/commands/list.c
+++ b/src/common/cli/directives/commands/list.c
@@ -58,7 +58,7 @@ static bool find_max_pkg_name_len(size_t *len) {
   return ret;
 }
 
-static void simple_print() {
+static void simple_print(void) {
   char *pkg_dir = NULL;
   os_fs_tm_dypkgs(&pkg_dir);
 
diff --git a/src/common/cli/directives/commands/test.c b/src/common/cli/directives/commands/test.c
index e9d98a2..b51c446 100644
--- a/src/common/cli/directives/commands/test.c
+++ b/src/common/cli/directives/commands/test.c
@@ -41,12 +41,12 @@
   cli_out_success("All tests passed");         \
   return EXIT_SUCCESS;
 
-// static bool test_tar() {
+// static bool test_tar(void) {
 //   cli_out_progress("Testing tar extraction...");
 //   return archive_tar_extract("extract", "archive.tar");
 // }
 
-static bool test_dypath() {
+static bool test_dypath(void) {
   cli_out_progress("Testing dypath...");
   char *path;
   os_fs_tm_dyhome(&path);
@@ -54,7 +54,7 @@ static bool test_dypath() {
   return true;
 }
 
-static bool test_dirs() {
+static bool test_dirs(void) {
   cli_out_progress("Testing dir creation...");
   if (TM_FS_DIROP_STATUS_OK != os_fs_mkdir("test")) {
     return false;
@@ -78,7 +78,7 @@ static bool test_dirs() {
   return true;
 }
 
-static bool test_init() {
+static bool test_init(void) {
   cli_out_progress("Testing fs init...");
   return os_fs_tm_init();
 }
diff --git a/src/common/cli/directives/lookup.c b/src/common/cli/directives/lookup.c
index 611a2cd..ecfc774 100644
--- a/src/common/cli/directives/lookup.c
+++ b/src/common/cli/directives/lookup.c
@@ -197,13 +197,13 @@ bool cli_lkup_option(const char *option, cli_drt_desc_t *dst) {
       options, sizeof options / sizeof(cli_drt_desc_t), option, dst);
 }
 
-cli_lkup_table_t cli_lkup_cmdtable() {
+cli_lkup_table_t cli_lkup_cmdtable(void) {
   return (cli_lkup_table_t){.table = commands,
                             .num_entries =
                                 sizeof commands / sizeof(cli_drt_desc_t)};
 }
 
-cli_lkup_table_t cli_lkup_opttable() {
+cli_lkup_table_t cli_lkup_opttable(void) {
   return (cli_lkup_table_t){
       .table = options, .num_entries = sizeof options / sizeof(cli_drt_desc_t)};
 }
diff --git a/src/common/cli/input.c b/src/common/cli/input.c
index 292f29a..b81ec34 100644
--- a/src/common/cli/input.c
+++ b/src/common/cli/input.c
@@ -26,7 +26,7 @@
 #include "cli/output.h"
 #include "stream.h"
 
-static void clear_input_stream() {
+static void clear_input_stream(void) {
   char ch = 0;
   while (32 < (ch = getchar()) && !feof(stdin))
     ;
diff --git a/src/common/cli/output.c b/src/common/cli/output.c
index 4262120..2e295a6 100644
--- a/src/common/cli/output.c
+++ b/src/common/cli/output.c
@@ -80,14 +80,14 @@ static void aligned_vprintf(const char *fmt, va_list args, size_t pad) {
   }
 }
 
-void cli_out_newline() {
+void cli_out_newline(void) {
   if (!last_is_newline) {
     puts("");
     last_is_newline = true;
   }
 }
 
-void cli_out_reset() {
+void cli_out_reset(void) {
   last_is_newline = false;
 }
 
diff --git a/src/common/tm-mem.c b/src/common/tm-mem.c
index 5fc9e31..e12142b 100644
--- a/src/common/tm-mem.c
+++ b/src/common/tm-mem.c
@@ -26,7 +26,7 @@ void mem_safe_free(void *ptr) {
   }
 }
 
-void mem_oom() {
+void mem_oom(void) {
   cli_out_error("Unable to allocate memory, probably ran out of memory. "
                 "Exiting now");
   exit(EXIT_FAILURE);
diff --git a/src/os-common/no-optional/console.c b/src/os-common/no-optional/console.c
index c71426e..7989e8e 100644
--- a/src/os-common/no-optional/console.c
+++ b/src/os-common/no-optional/console.c
@@ -20,7 +20,7 @@
 
 #include "os/no-optional/console.h"
 
-csz_t noopt_console_get_sz() {
+csz_t noopt_console_get_sz(void) {
   return (csz_t){.rows = 40, .columns = 80};
 }
 
diff --git a/src/os-common/posix/console.c b/src/os-common/posix/console.c
index f8b21b5..2e4d1b5 100644
--- a/src/os-common/posix/console.c
+++ b/src/os-common/posix/console.c
@@ -28,7 +28,7 @@
 
 #include "os/console.h"
 
-csz_t posix_console_get_sz() {
+csz_t posix_console_get_sz(void) {
   struct winsize size;
   ioctl(STDOUT_FILENO, TIOCGWINSZ, &size);
   return (csz_t){.rows = size.ws_row, .columns = size.ws_col};
diff --git a/src/os-common/posix/fs.c b/src/os-common/posix/fs.c
index 9186609..ec13cad 100644
--- a/src/os-common/posix/fs.c
+++ b/src/os-common/posix/fs.c
@@ -48,7 +48,7 @@ static tmstr_t Plugins    = {0};
 static tmstr_t PluginConf = {0};
 static tmstr_t Path       = {0};
 
-static const char *get_home_directory() {
+static const char *get_home_directory(void) {
   struct passwd *pw = getpwuid(getuid());
   return pw->pw_dir;
 }
@@ -61,7 +61,7 @@ static fs_dirop_status_t simplify(fs_dirop_status_t s) {
   return s;
 }
 
-static fs_dirop_status_t translate_direrr() {
+static fs_dirop_status_t translate_direrr(void) {
   switch (errno) {
   case EACCES:
     return TM_FS_DIROP_STATUS_PERM;
@@ -78,7 +78,7 @@ static fs_dirop_status_t translate_direrr() {
   }
 }
 
-static fs_fileop_status_t translate_fileerr() {
+static fs_fileop_status_t translate_fileerr(void) {
   switch (errno) {
   case EACCES:
     return TM_FS_FILEOP_STATUS_PERM;
@@ -503,7 +503,7 @@ size_t posix_fs_tm_dyexecpath(const char **dst, const char *exec) {
   return ret;
 }
 
-bool posix_fs_tm_init() {
+bool posix_fs_tm_init(void) {
   const char *usr_home = get_home_directory();
 
   Home.len  = os_fs_path_dyconcat(&Home.buf, 2, usr_home, ".tarman");
diff --git a/src/os-specific/darwin/console.c b/src/os-specific/darwin/console.c
index 41ee949..d56bdb5 100644
--- a/src/os-specific/darwin/console.c
+++ b/src/os-specific/darwin/console.c
@@ -20,7 +20,7 @@
 
 #include "os/console.h"
 
-csz_t os_console_get_sz() {
+csz_t os_console_get_sz(void) {
   return posix_console_get_sz();
 }
 
diff --git a/src/os-specific/darwin/fs.c b/src/os-specific/darwin/fs.c
index cc631a2..074dc5a 100644
--- a/src/os-specific/darwin/fs.c
+++ b/src/os-specific/darwin/fs.c
@@ -147,6 +147,6 @@ size_t os_fs_tm_dyplugconf(const char **dst, const char *plugin) {
   return posix_fs_tm_dyplugconf(dst, plugin);
 }
 
-bool os_fs_tm_init() {
+bool os_fs_tm_init(void) {
   return posix_fs_tm_init();
 }
diff --git a/src/os-specific/linux/console.c b/src/os-specific/linux/console.c
index 41ee949..d56bdb5 100644
--- a/src/os-specific/linux/console.c
+++ b/src/os-specific/linux/console.c
@@ -20,7 +20,7 @@
 
 #include "os/console.h"
 
-csz_t os_console_get_sz() {
+csz_t os_console_get_sz(void) {
   return posix_console_get_sz();
 }
 
diff --git a/src/os-specific/linux/env.c b/src/os-specific/linux/env.c
index 240e294..c8626a0 100644
--- a/src/os-specific/linux/env.c
+++ b/src/os-specific/linux/env.c
@@ -26,7 +26,7 @@
 #include "os/posix/env.h"
 #include "tm-mem.h"
 
-static const char *get_home_directory() {
+static const char *get_home_directory(void) {
   struct passwd *pw = getpwuid(getuid());
   return pw->pw_dir;
 }
diff --git a/src/os-specific/linux/fs.c b/src/os-specific/linux/fs.c
index e159554..8168060 100644
--- a/src/os-specific/linux/fs.c
+++ b/src/os-specific/linux/fs.c
@@ -147,6 +147,6 @@ size_t os_fs_tm_dyplugconf(const char **dst, const char *plugin) {
   return posix_fs_tm_dyplugconf(dst, plugin);
 }
 
-bool os_fs_tm_init() {
+bool os_fs_tm_init(void) {
   return posix_fs_tm_init();
 }