diff --git a/src/apps/miscapps/generateBaseCellNeighbors.c b/src/apps/miscapps/generateBaseCellNeighbors.c
index e585694ea..2b22469e6 100644
--- a/src/apps/miscapps/generateBaseCellNeighbors.c
+++ b/src/apps/miscapps/generateBaseCellNeighbors.c
@@ -81,7 +81,7 @@ static void auditBaseCellNeighbors(int baseCellNeighbors[NUM_BASE_CELLS][7],
 /**
  * Generates and prints the baseCellNeighbors and baseCellRotations tables.
  */
-static void generate() {
+static void generate(void) {
     int baseCellNeighbors[NUM_BASE_CELLS][7];
     int baseCellRotations[NUM_BASE_CELLS][7];
 
diff --git a/src/apps/miscapps/generateFaceCenterPoint.c b/src/apps/miscapps/generateFaceCenterPoint.c
index 6535246d1..027c6e63c 100644
--- a/src/apps/miscapps/generateFaceCenterPoint.c
+++ b/src/apps/miscapps/generateFaceCenterPoint.c
@@ -52,7 +52,7 @@ const LatLng faceCenterGeoCopy[NUM_ICOSA_FACES] = {
 /**
  * Generates and prints the faceCenterPoint table.
  */
-static void generate() {
+static void generate(void) {
     printf("static const Vec3d faceCenterPoint[NUM_ICOSA_FACES] = {\n");
     for (int i = 0; i < NUM_ICOSA_FACES; i++) {
         LatLng centerCoords = faceCenterGeoCopy[i];
diff --git a/src/apps/miscapps/generatePentagonDirectionFaces.c b/src/apps/miscapps/generatePentagonDirectionFaces.c
index 985d0a904..468d238bb 100644
--- a/src/apps/miscapps/generatePentagonDirectionFaces.c
+++ b/src/apps/miscapps/generatePentagonDirectionFaces.c
@@ -25,7 +25,7 @@
 #include "baseCells.h"
 #include "h3Index.h"
 
-static void generate() {
+static void generate(void) {
     H3Index pentagons[NUM_PENTAGONS] = {0};
     // Get the res 2 pentagons, whose neighbors have the same base cell
     // and are unambiguously on the correct faces
diff --git a/src/h3lib/include/h3api.h.in b/src/h3lib/include/h3api.h.in
index 6d9be68be..58f6d9e84 100644
--- a/src/h3lib/include/h3api.h.in
+++ b/src/h3lib/include/h3api.h.in
@@ -437,7 +437,7 @@ DECLSPEC H3Error H3_EXPORT(getNumCells)(int res, int64_t *out);
  * @{
  */
 /** @brief returns the number of resolution 0 cells (hexagons and pentagons) */
-DECLSPEC int H3_EXPORT(res0CellCount)();
+DECLSPEC int H3_EXPORT(res0CellCount)(void);
 
 /** @brief provides all base cells in H3Index format*/
 DECLSPEC H3Error H3_EXPORT(getRes0Cells)(H3Index *out);
@@ -448,7 +448,7 @@ DECLSPEC H3Error H3_EXPORT(getRes0Cells)(H3Index *out);
  * @{
  */
 /** @brief returns the number of pentagons per resolution */
-DECLSPEC int H3_EXPORT(pentagonCount)();
+DECLSPEC int H3_EXPORT(pentagonCount)(void);
 
 /** @brief generates all pentagons at the specified resolution */
 DECLSPEC H3Error H3_EXPORT(getPentagons)(int res, H3Index *out);
diff --git a/src/h3lib/lib/baseCells.c b/src/h3lib/lib/baseCells.c
index 57e643855..1b971d620 100644
--- a/src/h3lib/lib/baseCells.c
+++ b/src/h3lib/lib/baseCells.c
@@ -919,7 +919,7 @@ Direction _getBaseCellDirection(int originBaseCell, int neighboringBaseCell) {
  *
  * @return int count of resolution 0 cells
  */
-int H3_EXPORT(res0CellCount)() { return NUM_BASE_CELLS; }
+int H3_EXPORT(res0CellCount)(void) { return NUM_BASE_CELLS; }
 
 /**
  * getRes0Cells generates all base cells storing them into the provided
diff --git a/src/h3lib/lib/h3Index.c b/src/h3lib/lib/h3Index.c
index 25fff0a36..bccd4baf5 100644
--- a/src/h3lib/lib/h3Index.c
+++ b/src/h3lib/lib/h3Index.c
@@ -1019,7 +1019,7 @@ H3Error H3_EXPORT(getIcosahedronFaces)(H3Index h3, int *out) {
  *
  * @return int count of pentagon indexes
  */
-int H3_EXPORT(pentagonCount)() { return NUM_PENTAGONS; }
+int H3_EXPORT(pentagonCount)(void) { return NUM_PENTAGONS; }
 
 /**
  * Generates all pentagons at the specified resolution
diff --git a/src/h3lib/lib/iterators.c b/src/h3lib/lib/iterators.c
index 5cbe57f63..ac68fd1ef 100644
--- a/src/h3lib/lib/iterators.c
+++ b/src/h3lib/lib/iterators.c
@@ -42,7 +42,7 @@ static void _incrementResDigit(IterCellsChildren *it, int res) {
  * internal state after it's exhausted, like the child resolution, for
  * example.
  */
-static IterCellsChildren _null_iter() {
+static IterCellsChildren _null_iter(void) {
     return (IterCellsChildren){
         .h = H3_NULL, ._parentRes = -1, ._skipDigit = -1};
 }
diff --git a/website/docs/api/misc.mdx b/website/docs/api/misc.mdx
index f3a1cd9bc..d643f55a8 100644
--- a/website/docs/api/misc.mdx
+++ b/website/docs/api/misc.mdx
@@ -759,7 +759,7 @@ parents of all other cell indexes in the H3 grid system. The returned indexes co
 <TabItem value="c">
 
 ```c
-int res0CellCount();
+int res0CellCount(void);
 ```
 
 </TabItem>
@@ -864,7 +864,7 @@ Returns 0 (`E_SUCCESS`) on success.
 <TabItem value="c">
 
 ```c
-int pentagonCount();
+int pentagonCount(void);
 ```
 
 </TabItem>
diff --git a/website/versioned_docs/version-3.x/api/misc.mdx b/website/versioned_docs/version-3.x/api/misc.mdx
index d7ca32c66..f331720d2 100644
--- a/website/versioned_docs/version-3.x/api/misc.mdx
+++ b/website/versioned_docs/version-3.x/api/misc.mdx
@@ -704,7 +704,7 @@ All the resolution 0 H3 indexes.
 <TabItem value="c">
 
 ```c
-int res0IndexCount();
+int res0IndexCount(void);
 ```
 
 </TabItem>
@@ -807,7 +807,7 @@ All the pentagon H3 indexes at the specified resolution.
 <TabItem value="c">
 
 ```c
-int pentagonIndexCount();
+int pentagonIndexCount(void);
 ```
 
 </TabItem>