diff --git a/include/mgba/internal/ds/gx/software.h b/include/mgba/internal/ds/gx/software.h
index 7c75cd69b..c9201da24 100644
--- a/include/mgba/internal/ds/gx/software.h
+++ b/include/mgba/internal/ds/gx/software.h
@@ -20,8 +20,8 @@ struct DSGXSoftwarePolygon {
 	uint16_t* texBase;
 	uint16_t* palBase;
 	int texFormat;
-	unsigned texW;
-	unsigned texH;
+	int texW;
+	int texH;
 	int32_t topY;
 	int32_t bottomY;
 	int32_t topZ;
diff --git a/src/ds/gx/software.c b/src/ds/gx/software.c
index 64bbada2f..8e6973391 100644
--- a/src/ds/gx/software.c
+++ b/src/ds/gx/software.c
@@ -43,8 +43,8 @@ static color_t _lookupColor(struct DSGXSoftwareEndpoint* ep, struct DSGXSoftware
 	// TODO: Optimize
 	uint16_t texel;
 
-	uint16_t s = ep->s >> 4;
-	uint16_t t = ep->t >> 4;
+	int16_t s = ep->s >> 4;
+	int16_t t = ep->t >> 4;
 	if (!DSGXTexParamsIsSRepeat(poly->poly->texParams)) {
 		if (s < 0) {
 			s = 0;
@@ -62,7 +62,7 @@ static color_t _lookupColor(struct DSGXSoftwareEndpoint* ep, struct DSGXSoftware
 	if (!DSGXTexParamsIsTRepeat(poly->poly->texParams)) {
 		if (t < 0) {
 			t = 0;
-		} else if (s >= poly->texH) {
+		} else if (t >= poly->texH) {
 			t = poly->texW - 1;
 		}
 	} else if (DSGXTexParamsIsTMirror(poly->poly->texParams)) {