diff --git a/src/Makefile b/src/Makefile
index 3261324d4..150e3c142 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -107,6 +107,7 @@ CFLAGS                  += -Wundef
 CFLAGS                  += -Wshadow
 CFLAGS                  += -Wmissing-declarations
 CFLAGS                  += -Wmissing-prototypes
+CFLAGS                  += -Wpointer-arith
 CFLAGS                  += -ftrapv
 
 LFLAGS                  :=
diff --git a/src/potfile.c b/src/potfile.c
index 43e357ab2..da26cea26 100644
--- a/src/potfile.c
+++ b/src/potfile.c
@@ -127,7 +127,7 @@ void *hc_bsearch_r (const void *key, const void *base, size_t nmemb, size_t size
 
     const size_t c = l + m;
 
-    const void *next = base + (c * size);
+    const char *next = (char *) base + (c * size);
 
     const int cmp = (*compar) (key, next, arg);