diff --git a/src/hbas.c b/src/hbas.c
index 5e810fe..bd8ae6e 100644
--- a/src/hbas.c
+++ b/src/hbas.c
@@ -29,6 +29,7 @@ SOFTWARE.
 #include "error.h"
 #include "instructions.c"
 #include "hash.c"
+#include "register.c"
 
 void hd(char *data, size_t len)
 {
@@ -381,37 +382,6 @@ size_t label_lookup(LabelVec *labels, char *name, size_t len)
     return INVALID;
 }
 
-int parse_register(char *name, size_t len)
-{
-    if (name[0] != 'r')
-    {
-        return 256; // Register name should start with 'r'
-    }
-    if (len > 4)
-    {
-        return 256; // Register name too long
-    }
-    uint16_t rv = 0;
-    if (len > 2 && name[1] == '0')
-    {
-        return 256; // Extra zero suffix
-    }
-    for (size_t ii = 1; ii < len; ii += 1)
-    {
-        char chr = name[ii];
-        if (!(chr >= '0' && chr <= '9'))
-        {
-            return 256; // Register name must only contain numbers
-        }
-        rv = rv * 10 + (chr - '0');
-    }
-    if (rv > 255)
-    {
-        return 256; // Register number too large
-    }
-    return (int)rv;
-}
-
 // safety: assumes the buffer has enough place for specified integer size
 AsmError push_int_le(char *buf, uint64_t val, size_t size, uint8_t sign)
 {
diff --git a/src/register.c b/src/register.c
new file mode 100644
index 0000000..ee8637c
--- /dev/null
+++ b/src/register.c
@@ -0,0 +1,30 @@
+int parse_register(char *name, size_t len)
+{
+    if (name[0] != 'r')
+    {
+        return 256; // Register name should start with 'r'
+    }
+    if (len > 4)
+    {
+        return 256; // Register name too long
+    }
+    uint16_t rv = 0;
+    if (len > 2 && name[1] == '0')
+    {
+        return 256; // Extra zero suffix
+    }
+    for (size_t ii = 1; ii < len; ii += 1)
+    {
+        char chr = name[ii];
+        if (!(chr >= '0' && chr <= '9'))
+        {
+            return 256; // Register name must only contain numbers
+        }
+        rv = rv * 10 + (chr - '0');
+    }
+    if (rv > 255)
+    {
+        return 256; // Register number too large
+    }
+    return (int)rv;
+}
\ No newline at end of file