diff --git a/DESCRIPTION b/DESCRIPTION
index 2b54edc..3f06791 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -10,7 +10,7 @@ Authors@R: c(
 Description: Provides access to Uber's 'H3' geospatial indexing system via 'h3lib' 
   <https://CRAN.R-project.org/package=h3lib>. 'h3r' is designed to mimic the 'H3' 
   Application Programming Interface (API) <https://h3geo.org/docs/api/indexing/>, 
-  so that any function in the API is also availble in 'h3r'.
+  so that any function in the API is also available in 'h3r'.
 License: MIT + file LICENSE
 URL: https://symbolixau.github.io/h3r/
 BugReports: https://github.com/symbolixau/h3r/issues
diff --git a/src/h3r.h b/src/h3r.h
index 3677342..7e204de 100644
--- a/src/h3r.h
+++ b/src/h3r.h
@@ -88,11 +88,11 @@ SEXP h3rEdgeLengthM(SEXP edge);
 SEXP h3rEdgeLengthKm(SEXP edge);
 
 SEXP h3rGetNumCells(SEXP res);
-SEXP h3rGetRes0Cells();
-SEXP h3rRes0CellCount();
+SEXP h3rGetRes0Cells(void);
+SEXP h3rRes0CellCount(void);
 
 SEXP h3rGetPentagons(SEXP res);
-SEXP h3rPentagonCount();
+SEXP h3rPentagonCount(void);
 
 SEXP h3rGreatCircleDistance(SEXP aLats, SEXP aLons, SEXP bLats, SEXP bLons, int distType);
 SEXP h3rGreatCircleDistanceRads(SEXP aLats, SEXP aLons, SEXP bLats, SEXP bLons);
diff --git a/src/h3rMiscellaneous.c b/src/h3rMiscellaneous.c
index 5fe0651..4d068e7 100644
--- a/src/h3rMiscellaneous.c
+++ b/src/h3rMiscellaneous.c
@@ -205,7 +205,7 @@ SEXP h3rGetNumCells(SEXP res) {
   return out;
 }
 
-SEXP h3rGetRes0Cells() {
+SEXP h3rGetRes0Cells(void) {
   int i;
   int count = res0CellCount();
 
@@ -224,7 +224,7 @@ SEXP h3rGetRes0Cells() {
   return out;
 }
 
-SEXP h3rRes0CellCount() {
+SEXP h3rRes0CellCount(void) {
 
   SEXP out = PROTECT(Rf_allocVector(INTSXP, 1));
 
@@ -267,7 +267,7 @@ SEXP h3rGetPentagons(SEXP res) {
   return out;
 }
 
-SEXP h3rPentagonCount() {
+SEXP h3rPentagonCount(void) {
 
   SEXP out = PROTECT(Rf_allocVector(INTSXP, 1));