diff --git a/as/assemble.c b/as/assemble.c
index c0caf0c..09cd111 100644
--- a/as/assemble.c
+++ b/as/assemble.c
@@ -8,6 +8,7 @@
 #include "assemble.h"
 #include "hashtab.h"
 #include "tunit.h"
+#include "pdp10-extint.h"
 
 static int assemble_section(struct hashnode *hashnode, void *data)
 {
@@ -23,10 +24,10 @@ static int assemble_section(struct hashnode *hashnode, void *data)
 
     section->dot = (section->dot + 3) & ~(unsigned long)3;
 
-    section->image_words = malloc((section->dot / 4) * sizeof(pdp10_uint36_t));
-    if (!section->image_words) {
+    section->image = malloc(section->dot * sizeof(pdp10_uint9_t));
+    if (!section->image) {
 	fprintf(stderr, "%s: %s: failed to allocate %zu bytes for text image: %s\n",
-		tunit->progname, __FUNCTION__, (section->dot / 4) * sizeof(pdp10_uint36_t), strerror(errno));
+		tunit->progname, __FUNCTION__, section->dot * sizeof(pdp10_uint9_t), strerror(errno));
 	return -1;
     }
 
@@ -50,16 +51,23 @@ static int assemble_section(struct hashnode *hashnode, void *data)
 	}
 	case S_INSN:
 	{
+	    pdp10_uint36_t word;
+	    struct pdp10_ext_uint36 ext36;
+	    unsigned int i;
+
 	    if (dot >= section->dot) {
 		fprintf(stderr, "%s: %s: internal error: text image overflow\n", tunit->progname, __FUNCTION__);
 		return -1;
 	    }
-	    section->image_words[dot / 4] =
+	    word =
 		((pdp10_uint36_t)(stmt->u.insn.opcode & 0x1FF) << (36 - 9)
 		 | ((stmt->u.insn.accumulator & 0xF) << (36 - 13))
 		 | ((stmt->u.insn.at & 1) << (36 - 14))
 		 | ((stmt->u.insn.indexreg & 0xF) << (36 - 18))
 		 | (stmt->u.insn.address & PDP10_UINT18_MAX));
+	    pdp10_uint36_to_ext(word, &ext36);
+	    for (i = 0; i < 4; ++i)
+		section->image[dot + i] = ext36.nonet[i];
 	    dot += 4;
 	    break;
 	}
diff --git a/as/output.c b/as/output.c
index ba1d749..d984960 100644
--- a/as/output.c
+++ b/as/output.c
@@ -104,7 +104,7 @@ struct context {
 
 static int append_section(struct context *context, struct section *section)
 {
-    if (section->dot == 0 || section->image_words == NULL)
+    if (section->dot == 0 || section->image == NULL)
 	return 0;
 
     section->st_shndx = context->shnum;
@@ -154,15 +154,14 @@ static int output_section(struct hashnode *hashnode, void *data)
     struct context *context = data;
     unsigned int i;
 
-    if (section->dot == 0 || section->image_words == NULL)
+    if (section->dot == 0 || section->image == NULL)
 	return 0;
 
     if (output_section_prologue(context, section) < 0)
 	return -1;
 
-    /* XXX: ->image_words[] should be uint9_t[] not uint36_t[] */
-    for (i = 0; i < section->dot; i += 4)
-	if (pdp10_elf36_write_uint36(context->pdp10fp, section->image_words[i / 4]) < 0)
+    for (i = 0; i < section->dot; ++i)
+	if (pdp10_elf36_write_uint9(context->pdp10fp, section->image[i]) < 0)
 	    return -1;
 
     output_section_epilogue(context, section);
@@ -194,7 +193,7 @@ static int output_shdr(struct hashnode *hashnode, void *data)
     struct context *context = data;
 
 
-    if (section->dot == 0 || section->image_words == NULL)
+    if (section->dot == 0 || section->image == NULL)
 	return 0;
 
     return output_section_header(context, section);
@@ -286,7 +285,7 @@ int output(struct tunit *tunit, const char *outfile)
 	section_strtab.sh_type = SHT_STRTAB;
 	section_strtab.sh_addralign = 1;
 	section_strtab.dot = context.symstrtab.nrbytes; /* XXX: fixme */
-	section_strtab.image_words = (pdp10_uint36_t*)4; /* XXX: fixme */
+	section_strtab.image = (pdp10_uint9_t*)4; /* XXX: fixme */
 
 	if (append_section(&context, &section_strtab) < 0)
 	    return -1;
@@ -318,7 +317,7 @@ int output(struct tunit *tunit, const char *outfile)
 	section_symtab.sh_link = section_strtab.st_shndx;
 	section_symtab.sh_addralign = 4;	/* XXX: PDP10-specific */
 	section_symtab.dot = context.symnum * ELF36_SYM_SIZEOF; /* XXX: fixme */
-	section_symtab.image_words = (pdp10_uint36_t*)symtab; /* XXX: fixme */
+	section_symtab.image = (pdp10_uint9_t*)symtab; /* XXX: fixme */
 
 	if (append_section(&context, &section_symtab) < 0)
 	    return -1;
@@ -336,7 +335,7 @@ int output(struct tunit *tunit, const char *outfile)
 	    return -1;
 
 	section_shstrtab.dot = context.shstrtab.nrbytes; /* XXX: fixme */
-	section_shstrtab.image_words = (pdp10_uint36_t*)4; /* XXX: fixme */
+	section_shstrtab.image = (pdp10_uint9_t*)4; /* XXX: fixme */
 
 	section_shstrtab.st_shndx = context.shnum;
 	++context.shnum;
@@ -406,7 +405,7 @@ int output(struct tunit *tunit, const char *outfile)
 	if (output_section_prologue(&context, &section_symtab) < 0)
 	    return -1;
 
-	symtab = (Elf36_Sym*)section_symtab.image_words;
+	symtab = (Elf36_Sym*)section_symtab.image;
 
 	for (i = 0; i < context.symnum; ++i)
 	    if (pdp10_elf36_write_sym(context.pdp10fp, &symtab[i]) < 0)
diff --git a/as/tunit.c b/as/tunit.c
index 6cf3fea..610ad6d 100644
--- a/as/tunit.c
+++ b/as/tunit.c
@@ -49,7 +49,7 @@ void section_init(struct section *section, const char *name)
     section->head = NULL;
     section->tailptr = &section->head;
     section->dot = 0;
-    section->image_words = NULL;
+    section->image = NULL;
     section->st_shndx = 0;
     section->sh_name = 0;
     section->sh_type = SHT_NULL;
diff --git a/as/tunit.h b/as/tunit.h
index 2b510c3..8576241 100644
--- a/as/tunit.h
+++ b/as/tunit.h
@@ -50,7 +50,7 @@ struct section {
     const char *name;
     struct stmt *head, **tailptr;
     unsigned long dot;
-    pdp10_uint36_t *image_words;	/* assigned during assembly */
+    pdp10_uint9_t *image;		/* assigned during assembly */
     Elf36_Word st_shndx;		/* assigned during output */
     Elf36_Word sh_name;			/* assigned during output */
     Elf36_Word sh_type;