diff --git a/src/devices/imagedev/diablo.cpp b/src/devices/imagedev/diablo.cpp
index 2becfdf8bd1..64e313865bf 100644
--- a/src/devices/imagedev/diablo.cpp
+++ b/src/devices/imagedev/diablo.cpp
@@ -114,6 +114,7 @@ bool diablo_image_device::call_create(int create_format, util::option_resolution
 	UINT32 sectorsize, hunksize;
 	UINT32 cylinders, heads, sectors, totalsectors;
 
+	assert_always(create_args != nullptr, "Expected create_args to not be nullptr");
 	cylinders   = create_args->lookup_int('C');
 	heads       = create_args->lookup_int('H');
 	sectors     = create_args->lookup_int('S');
diff --git a/src/devices/imagedev/harddriv.cpp b/src/devices/imagedev/harddriv.cpp
index 87a6c758f38..42eeac477be 100644
--- a/src/devices/imagedev/harddriv.cpp
+++ b/src/devices/imagedev/harddriv.cpp
@@ -138,6 +138,7 @@ bool harddisk_image_device::call_create(int create_format, util::option_resoluti
 	UINT32 sectorsize, hunksize;
 	UINT32 cylinders, heads, sectors, totalsectors;
 
+	assert_always(create_args != nullptr, "Expected create_args to not be nullptr");
 	cylinders   = create_args->lookup_int('C');
 	heads       = create_args->lookup_int('H');
 	sectors     = create_args->lookup_int('S');
diff --git a/src/lib/util/opresolv.cpp b/src/lib/util/opresolv.cpp
index dabbbbc3334..7abe600cd65 100644
--- a/src/lib/util/opresolv.cpp
+++ b/src/lib/util/opresolv.cpp
@@ -437,9 +437,9 @@ const option_guide *option_resolution::index_option(int indx) const
 //	count_options
 // -------------------------------------------------
 
-int option_resolution::count_options(const option_guide *guide, const char *specification)
+size_t option_resolution::count_options(const option_guide *guide, const char *specification)
 {
-	int option_count = 0;
+	size_t option_count = 0;
 
 	while(guide->option_type != OPTIONTYPE_END)
 	{
diff --git a/src/lib/util/opresolv.h b/src/lib/util/opresolv.h
index 37c5339f02b..5faf615b30b 100644
--- a/src/lib/util/opresolv.h
+++ b/src/lib/util/opresolv.h
@@ -123,7 +123,7 @@ public:
 	const option_guide *index_option(int indx) const;
 
 	// processing option guides
-	static int count_options(const option_guide *guide, const char *specification);
+	static size_t count_options(const option_guide *guide, const char *specification);
 
 	// processing option specifications
 	static error list_ranges(const char *specification, int option_char,