diff --git a/include/asm/asm.h b/include/asm/asm.h
index 1bf97e79..231433aa 100644
--- a/include/asm/asm.h
+++ b/include/asm/asm.h
@@ -18,19 +18,23 @@
 
 #include "asm/localasm.h"
 
+#define MAXUNIONS		128
+#define MAXMACROARGS	256
+#define MAXINCPATHS		128
+
 extern SLONG nLineNo;
 extern ULONG nTotalLines;
 extern ULONG nPC;
 extern ULONG nPass;
 extern ULONG nIFDepth;
 extern bool skipElif;
+extern ULONG nUnionDepth;
+extern ULONG unionStart[MAXUNIONS];
+extern ULONG unionSize[MAXUNIONS];
 extern char tzCurrentFileName[_MAX_PATH + 1];
 extern struct Section *pCurrentSection;
 extern struct sSymbol *tHashedSymbols[HASHSIZE];
 extern struct sSymbol *pPCSymbol;
 extern bool oDontExpandStrings;
 
-#define MAXMACROARGS	256
-#define MAXINCPATHS		128
-
 #endif	/* //       ASM_H */
diff --git a/src/asm/asmy.y b/src/asm/asmy.y
index aff6737c..a4612e52 100644
--- a/src/asm/asmy.y
+++ b/src/asm/asmy.y
@@ -431,6 +431,34 @@ void	if_skip_to_endc()
 	nLineNo--;
 }
 
+void startUnion() {
+	if (!pCurrentSection) {
+		fatalerror("UNIONs must be inside a SECTION");
+	}
+	
+	ULONG unionIndex = nUnionDepth;
+	nUnionDepth++;
+	if (nUnionDepth > MAXUNIONS) {
+		fatalerror("Too many nested UNIONs");
+	}
+	
+	unionStart[unionIndex] = nPC;
+	unionSize[unionIndex] = 0;
+}
+
+void updateUnion() {
+	ULONG unionIndex = nUnionDepth - 1;
+	ULONG size = nPC - unionStart[unionIndex];
+	
+	if (size > unionSize[unionIndex]) {
+		unionSize[unionIndex] = size;
+	}
+	
+	nPC = unionStart[unionIndex];
+	pCurrentSection->nPC = unionStart[unionIndex];
+	pPCSymbol->nValue = unionStart[unionIndex];
+}
+
 %}
 
 %union
@@ -506,6 +534,7 @@ void	if_skip_to_endc()
 %token	T_POP_MACRO
 %token	T_POP_ENDM
 %token	T_POP_RSRESET T_POP_RSSET
+%token	T_POP_UNION T_POP_NEXTU T_POP_ENDU
 %token	T_POP_INCBIN T_POP_REPT
 %token	T_POP_CHARMAP
 %token	T_POP_SHIFT
@@ -644,6 +673,9 @@ simple_pseudoop	:	include
 				|	section
 				|	rsreset
 				|	rsset
+				|	union
+				|	nextu
+				|	endu
 				|	incbin
 				|	charmap
 				|	rept
@@ -745,6 +777,31 @@ rb				:	T_LABEL T_POP_RB uconst
 					}
 ;
 
+union			:	T_POP_UNION {
+						startUnion();
+					};
+
+nextu			:	T_POP_NEXTU {
+						if (nUnionDepth <= 0) {
+							fatalerror("Found NEXTU outside of a UNION construct");
+						}
+	
+						updateUnion();
+					};
+
+endu			:	T_POP_ENDU {
+						if (nUnionDepth <= 0) {
+							fatalerror("Found ENDU outside of a UNION construct");
+						}
+						
+						updateUnion();
+	
+						nUnionDepth--;
+						nPC = unionStart[nUnionDepth] + unionSize[nUnionDepth];
+						pCurrentSection->nPC = nPC;
+						pPCSymbol->nValue = nPC;
+					};
+
 ds				:	T_POP_DS uconst
 					{ out_Skip( $2 ); }
 ;
diff --git a/src/asm/globlex.c b/src/asm/globlex.c
index 6cc74ebd..60703a32 100644
--- a/src/asm/globlex.c
+++ b/src/asm/globlex.c
@@ -331,6 +331,10 @@ struct sLexInitString staticstrings[] = {
 	{"else", T_POP_ELSE},
 	{"elif", T_POP_ELIF},
 	{"endc", T_POP_ENDC},
+	
+	{"union", T_POP_UNION},
+	{"nextu", T_POP_NEXTU},
+	{"endu", T_POP_ENDU},
 
 	{"wram0", T_SECT_WRAM0},
 	{"vram", T_SECT_VRAM},
diff --git a/src/asm/main.c b/src/asm/main.c
index e54b25fc..c35bf528 100644
--- a/src/asm/main.c
+++ b/src/asm/main.c
@@ -22,8 +22,9 @@ char **cldefines;
 
 clock_t nStartClock, nEndClock;
 SLONG nLineNo;
-ULONG nTotalLines, nPass, nPC, nIFDepth, nErrors;
+ULONG nTotalLines, nPass, nPC, nIFDepth, nUnionDepth, nErrors;
 bool skipElif;
+ULONG unionStart[128], unionSize[128];
 
 extern int yydebug;
 
@@ -416,6 +417,7 @@ main(int argc, char *argv[])
 	nTotalLines = 0;
 	nIFDepth = 0;
 	skipElif = true;
+	nUnionDepth = 0;
 	nPC = 0;
 	nPass = 1;
 	nErrors = 0;
@@ -438,11 +440,16 @@ main(int argc, char *argv[])
 	if (nIFDepth != 0) {
 		errx(1, "Unterminated IF construct (%ld levels)!", nIFDepth);
 	}
+	
+	if (nUnionDepth != 0) {
+		errx(1, "Unterminated UNION construct (%ld levels)!", nUnionDepth);
+	}
 
 	nTotalLines = 0;
 	nLineNo = 1;
 	nIFDepth = 0;
 	skipElif = true;
+	nUnionDepth = 0;
 	nPC = 0;
 	nPass = 2;
 	nErrors = 0;
diff --git a/src/asm/output.c b/src/asm/output.c
index fce458bf..34501f78 100644
--- a/src/asm/output.c
+++ b/src/asm/output.c
@@ -460,6 +460,8 @@ checkcodesection(void)
 	    pCurrentSection->nType != SECT_ROMX) {
 		fatalerror("Section '%s' cannot contain code or data (not ROM0 or ROMX)",
 		     pCurrentSection->pzName);
+	} else if (nUnionDepth > 0) {
+		fatalerror("UNIONs cannot contain code or data");
 	}
 }
 
@@ -613,6 +615,10 @@ out_FindSection(char *pzName, ULONG secttype, SLONG org, SLONG bank, SLONG align
 void
 out_SetCurrentSection(struct Section * pSect)
 {
+	if (nUnionDepth > 0) {
+		fatalerror("Cannot change the section within a UNION");
+	}
+	
 	pCurrentSection = pSect;
 	nPC = pSect->nPC;
 
@@ -651,12 +657,11 @@ out_NewAlignedSection(char *pzName, ULONG secttype, SLONG alignment, SLONG bank)
 }
 
 /*
- * Output an absolute byte
+ * Output an absolute byte (bypassing ROM/union checks)
  */
 void
-out_AbsByte(int b)
+out_AbsByteBypassCheck(int b)
 {
-	checkcodesection();
 	checksectionoverflow(1);
 	b &= 0xFF;
 	if (nPass == 2)
@@ -667,6 +672,16 @@ out_AbsByte(int b)
 	pPCSymbol->nValue += 1;
 }
 
+/*
+ * Output an absolute byte
+ */
+void
+out_AbsByte(int b)
+{
+	checkcodesection();
+	out_AbsByteBypassCheck(b);
+}
+
 void
 out_AbsByteGroup(char *s, int length)
 {
@@ -689,6 +704,9 @@ out_Skip(int skip)
 		pCurrentSection->nPC += skip;
 		nPC += skip;
 		pPCSymbol->nValue += skip;
+	} else if (nUnionDepth > 0) {
+		while (skip--)
+			out_AbsByteBypassCheck(CurrentOptions.fillchar);
 	} else {
 		checkcodesection();
 		while (skip--)
diff --git a/src/asm/rgbasm.5 b/src/asm/rgbasm.5
index d45cbafd..34b5a501 100644
--- a/src/asm/rgbasm.5
+++ b/src/asm/rgbasm.5
@@ -612,6 +612,41 @@ You can also include only part of a file with
 The example below includes 256 bytes from data.bin starting from byte 78.
 .Pp
 .Dl INCBIN \[dq]data.bin\[dq],78,256
+.Ss Unions
+Unions allow multiple memory allocations to share the same space in memory,
+like unions in C.
+This allows you to easily reuse memory for different purposes, depending on
+the game's state.
+.Pp
+You create unions using the
+.Ic UNION ,
+.Ic NEXTU
+and
+.Ic ENDU
+keywords.
+.Ic NEXTU
+lets you create a new block of allocations, and you may use it as many times
+within a union as necessary.
+.Pp
+.Bd -literal -offset indent
+UNION
+Name: ds 8
+Nickname: ds 8
+NEXTU
+Health: dw
+Something: ds 3
+Lives: db
+NEXTU
+Temporary: ds 19
+ENDU
+.Ed
+.Pp
+This union will use up 19 bytes, as this is the size of the largest block
+(the last one, containing 'Temporary').
+Of course, as 'Name', 'Health', and 'Temporary' all point to the same memory
+locations, writes to any one of these will affect values read from the others.
+.Pp
+Unions may be used in any section, but code and data may not be included.
 .Sh THE MACRO LANGUAGE
 .Pp
 .Ss Printing things during assembly