diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 7291ef9..588a0d4 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -26,3 +26,11 @@ jobs:
         run: make all
       - name: test
         run: make check
+
+  fmt-lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: jidicula/clang-format-action@v4.3.0
+        with:
+          fallback-style: "Google"
diff --git a/compat/getgrent_r.c b/compat/getgrent_r.c
index 0bd5295..586f041 100644
--- a/compat/getgrent_r.c
+++ b/compat/getgrent_r.c
@@ -30,81 +30,84 @@
 // Library.
 #if defined(BSD) || (defined(__linux__) && !defined(__GLIBC__))
 
+#include <errno.h>
 #include <grp.h>
 #include <stddef.h>
+#include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <errno.h>
 #include <string.h>
-#include <stdint.h>
 
 #define ALIGNBYTES (sizeof(uintptr_t) - 1)
-#define ALIGN(p)((((uintptr_t)(p) + ALIGNBYTES) & ~ALIGNBYTES))
-static unsigned atou(char **s)
-{
-	unsigned x;
-	for (x=0; **s-'0'<10U; ++*s) x=10*x+(**s-'0');
-	return x;
+#define ALIGN(p) ((((uintptr_t)(p) + ALIGNBYTES) & ~ALIGNBYTES))
+static unsigned atou(char **s) {
+  unsigned x;
+  for (x = 0; **s - '0' < 10U; ++*s) x = 10 * x + (**s - '0');
+  return x;
 }
 
-int fgetgrent_r(FILE *f, struct group *gr, char *line, size_t size, struct group **res)
-{
-	char *s, *mems;
-	size_t i, nmem, need;
-	int rv = 0;
-	int ep;
-	ptrdiff_t remain;
-	for (;;) {
-		line[size-1] = '\xff';
-		if ( (fgets(line, size, f) == NULL) || ferror(f) || (line[size-1] != '\xff') ) {
-			rv = (line[size-1] != '\xff') ? ERANGE : ENOENT;
-			line = 0;
-			gr = 0;
-			goto end;
-		}
-		ep = strcspn(line, "\n");
-		line[ep] = 0;
+int fgetgrent_r(FILE *f, struct group *gr, char *line, size_t size,
+                struct group **res) {
+  char *s, *mems;
+  size_t i, nmem, need;
+  int rv = 0;
+  int ep;
+  ptrdiff_t remain;
+  for (;;) {
+    line[size - 1] = '\xff';
+    if ((fgets(line, size, f) == NULL) || ferror(f) ||
+        (line[size - 1] != '\xff')) {
+      rv = (line[size - 1] != '\xff') ? ERANGE : ENOENT;
+      line = 0;
+      gr = 0;
+      goto end;
+    }
+    ep = strcspn(line, "\n");
+    line[ep] = 0;
 
-		s = line;
-		gr->gr_name = s++;
-		if (!(s = strchr(s, ':'))) continue;
+    s = line;
+    gr->gr_name = s++;
+    if (!(s = strchr(s, ':'))) continue;
 
-		*s++ = 0; gr->gr_passwd = s;
-		if (!(s = strchr(s, ':'))) continue;
+    *s++ = 0;
+    gr->gr_passwd = s;
+    if (!(s = strchr(s, ':'))) continue;
 
-		*s++ = 0; gr->gr_gid = atou(&s);
-		if (*s != ':') continue;
+    *s++ = 0;
+    gr->gr_gid = atou(&s);
+    if (*s != ':') continue;
 
-		*s++ = 0; mems = s;
-		break;
-	}
+    *s++ = 0;
+    mems = s;
+    break;
+  }
 
-	for (nmem=!!*s; *s; s++)
-		if (*s==',') ++nmem;
+  for (nmem = !!*s; *s; s++)
+    if (*s == ',') ++nmem;
 
-	++ep;
-	remain = (void *) &line[size] - (void *) &line[ep];
-	need = (sizeof(char *) * (nmem+1)) + ALIGNBYTES;
-	if (need > remain) {
-		rv = ERANGE;
-		line = 0;
-		gr = 0;
-		goto end;
-	}
-	memset(&line[ep], 0, need);
-	gr->gr_mem = (char **) ALIGN(&line[ep]);
+  ++ep;
+  remain = (void *)&line[size] - (void *)&line[ep];
+  need = (sizeof(char *) * (nmem + 1)) + ALIGNBYTES;
+  if (need > remain) {
+    rv = ERANGE;
+    line = 0;
+    gr = 0;
+    goto end;
+  }
+  memset(&line[ep], 0, need);
+  gr->gr_mem = (char **)ALIGN(&line[ep]);
 
-	if (*mems) {
-		gr->gr_mem[0] = mems;
-		for (s=mems, i=0; *s; s++)
-			if (*s==',') *s++ = 0, gr->gr_mem[++i] = s;
-		gr->gr_mem[++i] = 0;
-	} else {
-		gr->gr_mem[0] = 0;
-	}
+  if (*mems) {
+    gr->gr_mem[0] = mems;
+    for (s = mems, i = 0; *s; s++)
+      if (*s == ',') *s++ = 0, gr->gr_mem[++i] = s;
+    gr->gr_mem[++i] = 0;
+  } else {
+    gr->gr_mem[0] = 0;
+  }
 end:
-	*res = gr;
-	if(rv) errno = rv;
-	return rv;
+  *res = gr;
+  if (rv) errno = rv;
+  return rv;
 }
-#endif //#if defined(BSD) || defined(__linux__) && !defined(__GLIBC__)
+#endif  //#if defined(BSD) || defined(__linux__) && !defined(__GLIBC__)
diff --git a/compat/getpwent_r.c b/compat/getpwent_r.c
index f383f59..e7de338 100644
--- a/compat/getpwent_r.c
+++ b/compat/getpwent_r.c
@@ -30,57 +30,63 @@
 // Library.
 #if defined(BSD) || (defined(__linux__) && !defined(__GLIBC__))
 
+#include <errno.h>
 #include <pwd.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <errno.h>
 #include <string.h>
 
-static unsigned atou(char **s)
-{
-	unsigned x;
-	for (x=0; **s-'0'<10U; ++*s) x=10*x+(**s-'0');
-	return x;
+static unsigned atou(char **s) {
+  unsigned x;
+  for (x = 0; **s - '0' < 10U; ++*s) x = 10 * x + (**s - '0');
+  return x;
 }
 
-int fgetpwent_r(FILE *f, struct passwd *pw, char *line, size_t size, struct passwd **res)
-{
-	char *s;
-	int rv = 0;
-	for (;;) {
-		line[size-1] = '\xff';
-		if ( (fgets(line, size, f) == NULL) || ferror(f) || line[size-1] != '\xff' ) {
-			rv = (line[size-1] != '\xff') ? ERANGE : ENOENT;
-			line = 0;
-			pw = 0;
-			break;
-		}
-		line[strcspn(line, "\n")] = 0;
+int fgetpwent_r(FILE *f, struct passwd *pw, char *line, size_t size,
+                struct passwd **res) {
+  char *s;
+  int rv = 0;
+  for (;;) {
+    line[size - 1] = '\xff';
+    if ((fgets(line, size, f) == NULL) || ferror(f) ||
+        line[size - 1] != '\xff') {
+      rv = (line[size - 1] != '\xff') ? ERANGE : ENOENT;
+      line = 0;
+      pw = 0;
+      break;
+    }
+    line[strcspn(line, "\n")] = 0;
 
-		s = line;
-		pw->pw_name = s++;
-		if (!(s = strchr(s, ':'))) continue;
+    s = line;
+    pw->pw_name = s++;
+    if (!(s = strchr(s, ':'))) continue;
 
-		*s++ = 0; pw->pw_passwd = s;
-		if (!(s = strchr(s, ':'))) continue;
+    *s++ = 0;
+    pw->pw_passwd = s;
+    if (!(s = strchr(s, ':'))) continue;
 
-		*s++ = 0; pw->pw_uid = atou(&s);
-		if (*s != ':') continue;
+    *s++ = 0;
+    pw->pw_uid = atou(&s);
+    if (*s != ':') continue;
 
-		*s++ = 0; pw->pw_gid = atou(&s);
-		if (*s != ':') continue;
+    *s++ = 0;
+    pw->pw_gid = atou(&s);
+    if (*s != ':') continue;
 
-		*s++ = 0; pw->pw_gecos = s;
-		if (!(s = strchr(s, ':'))) continue;
+    *s++ = 0;
+    pw->pw_gecos = s;
+    if (!(s = strchr(s, ':'))) continue;
 
-		*s++ = 0; pw->pw_dir = s;
-		if (!(s = strchr(s, ':'))) continue;
+    *s++ = 0;
+    pw->pw_dir = s;
+    if (!(s = strchr(s, ':'))) continue;
 
-		*s++ = 0; pw->pw_shell = s;
-		break;
-	}
-	*res = pw;
-	if (rv) errno = rv;
-	return rv;
+    *s++ = 0;
+    pw->pw_shell = s;
+    break;
+  }
+  *res = pw;
+  if (rv) errno = rv;
+  return rv;
 }
-#endif //#if defined(BSD) || defined(__linux__) && !defined(__GLIBC__)
+#endif  //#if defined(BSD) || defined(__linux__) && !defined(__GLIBC__)
diff --git a/gen_getent.c b/gen_getent.c
index 6e0dfd6..b67b7b2 100644
--- a/gen_getent.c
+++ b/gen_getent.c
@@ -172,7 +172,7 @@ static int getspent_to_file(FILE *output) {
     }
     if (ret == NSS_STATUS_UNAVAIL) {
       perror("ERROR: failed to access shadow test data");
-      free(buffer);      
+      free(buffer);
       return 1;
     }
   } while (ret == NSS_STATUS_SUCCESS || ret == NSS_STATUS_TRYAGAIN);
diff --git a/nss_cache.h b/nss_cache.h
index 7cf6401..d1067a0 100644
--- a/nss_cache.h
+++ b/nss_cache.h
@@ -38,8 +38,8 @@
 
 #ifdef DEBUG
 #undef DEBUG
-#define DEBUG(fmt, ...)                \
-  do {                                 \
+#define DEBUG(fmt, ...)                  \
+  do {                                   \
     fprintf(stderr, fmt, ##__VA_ARGS__); \
   } while (0)
 #else
diff --git a/test/last_pw_errno_test.c b/test/last_pw_errno_test.c
index a3c1a4d..6316440 100644
--- a/test/last_pw_errno_test.c
+++ b/test/last_pw_errno_test.c
@@ -1,7 +1,7 @@
-#include <sys/types.h>
-#include <pwd.h>
 #include <errno.h>
+#include <pwd.h>
 #include <stdio.h>
+#include <sys/types.h>
 
 int main(int argc, char **argv) {
   setpwent();
@@ -9,8 +9,7 @@ int main(int argc, char **argv) {
     errno = 0;
     struct passwd *pw = getpwent();
     if (!pw) {
-      if (errno != 0)
-        printf("ERRNO: %u %m\n", errno);
+      if (errno != 0) printf("ERRNO: %u %m\n", errno);
       break;
     }
   }