diff --git a/internal/shader/expr.go b/internal/shader/expr.go
index a5b4ee2fa..753ea348e 100644
--- a/internal/shader/expr.go
+++ b/internal/shader/expr.go
@@ -195,14 +195,14 @@ func (cs *compileState) parseExpr(block *block, fname string, expr ast.Expr, mar
 			t = lhst
 		case lhst.Equal(&rhst):
 			t = lhst
-		case lhst.Main == shaderir.Float:
-			t = rhst
-		case rhst.Main == shaderir.Float:
+		case op2 == shaderir.MatrixMul && (lhst.Main == shaderir.Float || lhst.IsVector()) && rhst.IsMatrix():
 			t = lhst
-		case op2 == shaderir.MatrixMul && lhst.IsVector() && rhst.IsMatrix():
-			t = lhst
-		case op2 == shaderir.MatrixMul && lhst.IsMatrix() && rhst.IsVector():
+		case op2 == shaderir.MatrixMul && lhst.IsMatrix() && (rhst.Main == shaderir.Float || rhst.IsVector()):
 			t = rhst
+		case (lhst.Main == shaderir.Float || lhst.Main == shaderir.Int) && rhst.IsVector():
+			t = rhst
+		case lhst.IsVector() && (rhst.Main == shaderir.Float || rhst.Main == shaderir.Int):
+			t = lhst
 		default:
 			panic(fmt.Sprintf("shaderir: invalid expression: %s %s %s", lhst.String(), e.Op, rhst.String()))
 		}
diff --git a/internal/shader/syntax_test.go b/internal/shader/syntax_test.go
index 029338bf3..11e76ce4a 100644
--- a/internal/shader/syntax_test.go
+++ b/internal/shader/syntax_test.go
@@ -3291,3 +3291,53 @@ func Fragment(position vec4, texCoord vec2, color vec4) vec4 {
 		}
 	}
 }
+
+// Issue #2706
+func TestSyntaxScalarAndVector(t *testing.T) {
+	cases := []struct {
+		stmt string
+		err  bool
+	}{
+		{stmt: "a := vec2(1) + 1; var b vec2 = a; _ = b", err: false},
+		{stmt: "a := 1 + vec2(1); var b vec2 = a; _ = b", err: false},
+		{stmt: "a := vec2(1); b := 1; var c vec2 = a + b; _ = c", err: true},
+		{stmt: "a := vec2(1); b := 1; var c vec2 = b + a; _ = c", err: true},
+		{stmt: "a := vec2(1) + 1.0; var b vec2 = a; _ = b", err: false},
+		{stmt: "a := 1.0 + vec2(1); var b vec2 = a; _ = b", err: false},
+		{stmt: "a := vec2(1); b := 1.0; var c vec2 = a + b; _ = c", err: false},
+		{stmt: "a := vec2(1); b := 1.0; var c vec2 = b + a; _ = c", err: false},
+		{stmt: "a := vec2(1) + 1.1; var b vec2 = a; _ = b", err: false},
+		{stmt: "a := 1.1 + vec2(1); var b vec2 = a; _ = b", err: false},
+		{stmt: "a := vec2(1); b := 1.1; var c vec2 = a + b; _ = c", err: false},
+		{stmt: "a := vec2(1); b := 1.1; var c vec2 = b + a; _ = c", err: false},
+
+		{stmt: "a := ivec2(1) + 1; var b ivec2 = a; _ = b", err: false},
+		{stmt: "a := 1 + ivec2(1); var b ivec2 = a; _ = b", err: false},
+		{stmt: "a := ivec2(1); b := 1; var c ivec2 = a + b; _ = c", err: false},
+		{stmt: "a := ivec2(1); b := 1; var c ivec2 = b + a; _ = c", err: false},
+		{stmt: "a := ivec2(1) + 1.0; var b ivec2 = a; _ = b", err: false},
+		{stmt: "a := 1.0 + ivec2(1); var b ivec2 = a; _ = b", err: false},
+		{stmt: "a := ivec2(1); b := 1.0; var c ivec2 = a + b; _ = c", err: true},
+		{stmt: "a := ivec2(1); b := 1.0; var c ivec2 = b + a; _ = c", err: true},
+		{stmt: "a := ivec2(1) + 1.1; var b ivec2 = a; _ = b", err: true},
+		{stmt: "a := 1.1 + ivec2(1); var b ivec2 = a; _ = b", err: true},
+		{stmt: "a := ivec2(1); b := 1.1; var c ivec2 = a + b; _ = c", err: true},
+		{stmt: "a := ivec2(1); b := 1.1; var c ivec2 = b + a; _ = c", err: true},
+	}
+
+	for _, c := range cases {
+		stmt := c.stmt
+		src := fmt.Sprintf(`package main
+
+func Fragment(position vec4, texCoord vec2, color vec4) vec4 {
+	%s
+	return position
+}`, stmt)
+		_, err := compileToIR([]byte(src))
+		if err == nil && c.err {
+			t.Errorf("%s must return an error but does not", stmt)
+		} else if err != nil && !c.err {
+			t.Errorf("%s must not return nil but returned %v", stmt, err)
+		}
+	}
+}